Exhibit 99.1

EEI Financial Conference October 31 - November 3, 2010

2 Forward-Looking Statements This presentation contains forward-looking statements based on our current expectations, and neither Pinnacle West nor APS assumes any obligation to update these statements, even if our internal estimates change, except as required by applicable law. These forward-looking statements are often identified by words such as "estimate," "predict," "may," "believe," "plan," "expect," "require," "intend," "assume" and similar words. Because actual results may differ materially from expectations, we caution you not to place undue reliance on these statements. A number of factors could cause future results to differ materially from historical results, or from outcomes currently expected or sought by Pinnacle West or APS. In addition to the Risk Factors described in Item 1A of the Pinnacle West/APS Annual Report on Form 10-K for the fiscal year ended December 31, 2009, these factors include, but are not limited to: regulatory and judicial decisions, developments and proceedings; our ability to achieve timely and adequate rate recovery of our costs; our ability to reduce capital expenditures and other costs while maintaining reliability and customer service levels; variations in demand for electricity, including those due to weather, the general economy, customer and sales growth (or decline), and the effects of energy conservation measures; power plant performance and outages; volatile fuel and purchased power costs; fuel and water supply availability; new legislation or regulation including those relating to greenhouse gas emissions, renewable energy mandates and energy efficiency standards; our ability to meet renewable energy requirements and recover related costs, including returns on debt and equity capital; risks inherent in the operation of nuclear facilities, including spent fuel disposal uncertainty; competition in retail and wholesale power markets; the duration and severity of the economic decline in Arizona and current credit, financial and real estate market conditions; the cost of debt and equity capital and the ability to access capital markets when required; restrictions on dividends or other burdensome provisions in our credit agreements and Arizona Corporation Commission orders; our ability, or the ability of our subsidiaries, to meet debt service obligations; changes to our credit ratings; the investment performance of the assets of our nuclear decommissioning trust, pension, and other postretirement benefit plans and the resulting impact on future funding requirements; the liquidity of wholesale power markets and the use of derivative contracts in our business; potential shortfalls in insurance coverage; new accounting requirements or new interpretations of existing requirements; generation transmission and distribution facility and system conditions and operating costs; the ability to meet the anticipated future need for additional baseload generation and associated transmission facilities in our region; the willingness or ability of our counterparties and power plant participants to meet contractual or other obligations; technological developments affecting the electric industry; and economic and other conditions affecting SunCor Development Company's ability to dispose of its remaining assets and satisfy its debt obligations.

Corporate Overview

PNW: Our Value Proposition Delivering Superior Shareholder Returns Capitalizing onAttractive FundamentalsVertically integrated electric utilityHigh-growth service territoryDiversified energy mixOperational excellenceStrong, energetic leadership Compelling CapitalInvestment OpportunitiesGreen resources - solar, other renewables, nuclearTransmission expansionDistribution system growth Focusing onGreen ResourcesAbundant solar conditions in ArizonaOther renewablesNuclear expansion optionTransmission expansionEnergy efficiency ImprovingRegulatory EnvironmentConstructive retail regulatory settlementAttractive recovery mechanisms for renewables and energy efficiencyProgress on many issues last five yearsBuilding collaborative relationships Strengthening Financialand Risk ProfilesInvestment-grade credit ratings and adequate liquidityRisk reductionConvert growth into superior ROE$2.10 per share annual dividendOpportunities for multiple expansion

NYSE Ticker: PNWMarket Cap: $4 BillionEnterprise Value: $8 Billion At our core, we are an electric utility. Pinnacle West: Who We Are Pinnacle West: Who We Are Assets September 30, 2010 $12 Billion Vertically Integrated Electric Utility $12 Billion Non-Utility Subsidiaries $97 Million Other

Service Territory1.1 million customer accounts34,646 square milesCustomer Growth0.6% in 20091% average annual growth expected through 20123-4% historical average - well above industry averageResources6,288 MW owned/leased capacity1,958 MW contracted conventional resources in operation498 MW contracted renewables in operation or under development2009 Peak Demand - 7,218 MW Arizona's Largest and Longest-Serving Electric Utility Serving Arizona customers since 1887 - 15 years before statehood. Arizona Continental United States

A Leadership Team of Industry Veterans Our top executives have more than 130 combined years of creating shareholder value in the energy industry. Jim Hatfield SVP & CFO Don Robinson APS President & COO Randy Edington EVP & Chief Nuclear Officer Don Brandt Chairman & CEO Mark Schiavoni SVP Fossil Generation Dave Falck EVP, General Counsel & Secretary

Financial Overview

2009 Actual: $2.33 per share Guidance as of October 28, 20102010 $2.95 - $3.10 per share2011 Estimated to be within guidance range provided for 2010, with some opportunity for modestly exceeding the range Consolidated On-Going EPS EPS $2.33 $2.95 $3.10 Projected Improvement in on-going earnings of approximately 30% expected for 2010.

Top-Tier Dividend Yield Top-Tier Dividend Yield Sep. 30, 2009 Dec. 31, 2009 5.1% 4.7% Pinnacle West's annual dividend is $2.10 per share. Mar. 31, 2010 Jun 30, 2010 Sep. 30, 2010 2.0%

Credit Facilities Ratings Adequate Financing Access and Liquidity Capacity Borrower ($ Millions) MaturesAPS $ 489 Sep. '11 APS 500 Feb. '13PNW 200 Feb. '13 $1,189 Solid bank group No MAC clauses or "clean down" provisions PNW APSSenior Unsecured Moody's Baa3 Baa2 S&P BB+ BBB- Fitch - BBBOutlook Moody's Stable Stable S&P Positive Positive Fitch Stable Stable Our credit metrics have improved significantly over the past five years. 2010 Major Financing Activities Feb. $500 million APS revolver renewalFeb. $200 million PNW revolver renewalApril $253 million common stock offering

Multi-Pronged Approach to ROE Improvement We are actively working to improve our return on equity. Electricity Rate Increases Regulatory Framework Improvements Cost Savings Initiatives Efficiency and Effectiveness Throughout Organization Goal ROE Improvement

Cost Savings To Support Future Results Engaged, motivated workforce Effective, efficient execution Optimize assets and resources Better leverage technology Our cost management efforts will help improve financial results beyond those achievable through regulatory decisions. Enterprise-wide emphasis Cost Savings

Regulatory Overview

Kristin Mayes Chairman (Rep) Gary Pierce (Rep) Terms Through January 2011 Elected November 2008, Terms Through January 2013 Sandra Kennedy (Dem) Paul Newman (Dem) Bob Stump (Rep) Arizona Corporation Commissioners

Generic DocketsDecoupling and other financial mechanisms to promote energy efficiencyLine extensionsFeed-in tariffsRenewable transmissionEnergy efficiency rulesResource planning rulesNovember 2, 2010 General ElectionTwo seats on ballotSeven candidatesPreparation for 2011 Retail General Rate Case Filing Opportunities to Continue Improving Regulatory Dialogue

Progressive 2009 Regulatory Settlement Positions APS Well for Next Two Years APS' regulatory settlement contains a number of benefits for investors beginning in 2010. Strengthens APS' earned ROE and financial conditionSupports common dividendDemonstrates increased cooperation among APS, ACC Staff, residential consumer advocate (RUCO) and other intervenorsAllows opportunity to help shape Arizona's energy future outside continual rate casesProvides earnings support until next base rate caseEstimated pretax earnings benefits: $165 million, 2010; $180 million, 2011; and $254 million, 2012Establishes expedited process for future base rate casesAllows next rate case filing on or after June 1, 2011, for rate changes effective on or after July 1, 2012

Progressive 2009 Regulatory Settlement Settlement agreement terms Base rate increase $ 207 $ 207 $ 207 Line extensions treated as revenue 23 25 49 Pension and OPEB deferrals 13 29 Palo Verde depreciation reduction 34 Subtotals 230 245 319Less interim base rate surcharge that ended upon general rate case implementation (65) (65) (65)Total $ 165 $ 180 $ 254 Estimated Pretax Earnings Benefits ($ Millions) 2010 2011 2012 Settlement provisions include earnings support until next rate case.

Our Regulatory Mix Our Regulatory Mix Transmission16% Generation & Distribution84% ACC FERCEffective Date 1/1/2010 6/1/2010Test Year Ending 12/31/2007 12/31/2009 Rate Base $5.6 B $1.1 BEquity Layer 54% 51% Allowed ROE 11.00% 10.75% The bulk of APS' revenues come from our regulated retail rate base; we also have a meaningful transmission business. $6.7 Billion Total Approved Rate Base Most Recent Rate Decisions

APS Revenues by Recovery Mechanisms We have received supportive regulatory decisions providing more timely recovery. Test Year Historical Forecasted PSA TCA RES DSM* Base Rates Other** (CHART) $ Millions Regulated Electricity Revenue by Recovery Mechanism * Includes revenues from wholesale electricity and transmission sales, electricity and other commodity sales, EIS and other miscellaneous services.** 2009 includes actuals through November 2009 and one month of forecast data.

Constructive Transmission Rate Regulation Constructive Transmission Rate Regulation FERC Formula Rates adopted in 2008Adjusted annually with 10.75% allowed ROEBased on FERC Form 1 and certain projectionsRetail portion flows through ACC Transmission Cost Adjustor (TCA)Recent transmission revenue changes We have achieved constructive transmission rate treatment.

Operations Overview

AnnualGrowth (CHART) Millions 1.1 1.7 52% Arizona has ranked in the top five for population growth over the last 20 years. APS expects strong future customer growth, in spite of current economic slowdown. APS Customer Growth Positive Long-Term Demographics Superior Historical Growth

2009 Retail Customer, Sales And Revenue Mixes 2009 Retail Customer, Sales And Revenue Mixes Residential Commercial Industrial Other Customers Year-End 1.1 Million Retail Sales28,173 GWh Operating Revenues$3.0 Billion (CHART) (CHART) 8% 45% 47% 50% 6% 43% 11% 89%

Customer Satisfaction ... A Key Priority Our employees take pride in providing top-tier customer service. Our employees take pride in providing top-tier customer service. APS 2010 J.D. Power Residential Customer Survey Industry Average Rating Outstanding Residential Customer Satisfaction Rating Average Outage Minutes/Year (CHART) Lowering Outage TimePer Customer APS Industry Top Quartile

2009 APS Generation and Energy Fuel Mixes 2009 APS Generation and Energy Fuel Mixes Nuclear Coal Gas & Oil Purchased Power Energy Fuel Mix 34,514 GWh Generation Fuel Mix27,374 GWh Generation Capacity Mix 6,288 MW (CHART) (CHART)

Superior Power Plant Performance Superior Power Plant Performance APS Industry Nuclear Capacity Factors Our nuclear and coal plants are strong baseload resources. 88% 89% '03 '04 '05 '06 '07 '08 '09 (CHART) APS Industry Coal Performance Metrics 65% 82% '03 '04 '05 '06 '07 '08 '09 Consistent solid performance2,747 MW total managed capacity1,753 MW APS shareHighly experienced managementFleet operating strategyNew commercial availability metric measures plant reliability during high-demand periods and market responsiveness Returned to superior performance3,938 MW total managed capacity1,146 MW total APS share2014 goals:Consistent site capacity factor greater than 90% Operating costs excluding fuel less than $0.02/kWhTop-quartile safety20-year license extension requested December 2008 92%

A Well-Balanced Generation Portfolio' Fuel / Plant Location Units Dispatch Commercial Ops. Date Operator Ownership / Interest 1 Net Capacity (MW) Nuclear Palo Verde Wintersburg, AZ 1,2,3 Base 1986 - 1989 APS 29.1 1,146 Total Nuclear 1,146 Coal Cholla Joseph City, AZ 1,2,3 Base 1962 - 1980 APS 100 647 Four Corners Farmington, NM 1,2,3 Base 1963 - 1964 APS 100 560 Four Corners Farmington, NM 4,5 Base 1969 - 1970 APS 15 225 Navajo Page, AZ 1,2,3 Base 1974 - 1976 SRP 14 315 Total Coal 1,747 Gas/Oil - Combined Cycle Redhawk Arlington, AZ 1,2 Intermediate 2002 APS 100 984 West Phoenix Phoenix, AZ 1,2,3,4,5 Intermediate 1976 - 2003 APS 100 887 Total Gas/Oil - Combined Cycle 1,871 Gas/Oil - Steam Turbines Ocotillo Tempe, AZ 1,2 Peaking 1960 APS 100 220 Saguaro Red Rock, AZ 1,2 Peaking 1954 - 1955 APS 100 210 Total Gas/Oil - Steam Turbines 430 Gas/Oil - Combustion Turbines Sundance Casa Grande, AZ 10 Peaking 2002 APS 100 420 Yucca Yuma, AZ 6 Peaking 1971 - 2008 APS 100 243 Saguaro Red Rock, AZ 1,2,3 Peaking 1972 - 2002 APS 100 189 West Phoenix Phoenix, AZ 1,2 Peaking 1972 - 1973 APS 100 110 Ocotillo Tempe, AZ 1,2 Peaking 1972 - 1973 APS 100 110 Douglas Douglas, AZ 1 Peaking 1972 APS 100 16 Total Gas/Oil - Combustion Turbines 1,088 Solar Solar - CSP Trough Red Rock, AZ -- Variable 2005 APS 100 1.0 Solar - PV Prescott, AZ -- Variable 2002 - 2006 APS 100 3.0 Solar - PV STAR Center -- Variable 1999 - 2004 APS 100 0.3 Solar - PV Various -- Variable 1996 - 2005 APS 100 1.5 Total Solar 5.8 Total Generation Capacity 6,288 As of December 31, 2009 1 Includes leased generating plants.

Resource Planning, Renewables and Energy Efficiency

$ Millions Generation Transmission Distribution Other Projected APS Capital Expenditures (CHART) 6% Compound Annual Growth Rate APS Rate Base We have reduced capital expenditures based on current economic conditions, yet still expect strong rate base growth. $ Billions Projected APS CapEx Drives Strong Rate Base Growth

100 MW 970 MW 1032 MW 350 MW 4300 MW 1005 MW Legend NORTH SAGUARO N . GILA PALO VERDE - HASSAYAMPA YUCCA GILA BEND REDHAWK KYRENE WEST WING BAGDAD 2016 PINNACLE PEAK CHOLLA NAVAJO 2014 . 2014 CORONADO FLAGSTAFF ( APS ) 2013 2 0 1 0 SUNDANCE 2014 FOUR CORNERS DESERT BASIN Line Relocation 2014 Further Transmission Investment is Key 10-Year Transmission Plan (115kV and above):$520 million of new transmission investmentOver 270 miles of new linesIncreases import capability by 26% to metro Phoenix and 38% to YumaFERC formula rates and retail adjustor Working with regulators to identify transmission projects for renewables 4300 MW Planned linesExisting linesSolar potential area Wind potential area Strategic investment is needed to maintain reliability and bring diversified resources to our customers. 2012 DELANY 2012 MAZATZAL 2013 MORGAN 2010 2014

Renewable Energy (RES) Minimum RequirementsPortion of retail sales to be supplied by renewable resources5% by 201515% by 2025Distributed energy component30% of total requirement by 2012Energy Efficiency RequirementsIncreasing annually 2011 - 2020Cumulative energy savings as percent of retail sales3% by 20129.5% by 201522% by 2020Rules to be certified by Arizona Attorney General Near-Term Resource Planning Issues Arizona has stringent renewable energy and energy efficiency standards.

APS Strong Commitment to Renewable Energy December 2009 retail regulatory settlement provisions1.7 million MWh additional renewable generation in service by end of 2015About twice state Renewable Energy Standard requirementRequired resource additionsPhotovoltaic solar projectsArizona wind projectConstructive rate recovery until reflected in base rates through:Renewable Energy Surcharge Adjustor;Power Supply Adjustor; orTransmission Cost Adjustor 2009 retail settlement enhanced commitments and regulatory support.

Germany We intend to make Arizona the "Solar Capital of the World." Japan Solar Insolation Comparison (kWh/year) Japan's solar insolation comparable to Florida Arizona Germany - among countries with highest installed capacities despite Seattle-like weather conditions Arizona's World-Class Solar Potential

AZ Sun Program 100 MW photovoltaic solar plants to be owned by APSUp to $500 million capital investmentTo be in service in 2011 - 2014ProjectsAnnounced to date: 15 MW at Luke Air Force Base (mid-2011)18 MW Gila Bend project (late 2011)$150 million estimated capital expendituresAdditional projects under evaluationConstructive rate recovery APS plans to add 100 megawatts of owned solar photovoltaic generation by the end of 2014.

APS Recent Renewable Resource Projects Photovoltaic solar resourcesTurnkey contracts for ownership or long-term purchase power agreements to be 15-50 MW eachRequest for proposals issued January 2010Proposals received April 2010Target for final contracts - 4th quarter 2010Expected to supply portion of AZ Sun ProgramArizona wind project25-year purchase power agreement with 99 MW Perrin Ranch Wind Project in northern Arizona announced July 2010Facility expected to be operational in 2012Resulted from January 2010 wind request for proposals Substantial efforts underway to expand renewable energy for Arizona.

Remote switching Substation on-line monitoring Capacitor controls Distribution sensors Solar water heaters Small-scale wind turbines APS-owned rooftop solar AMI Community Power Project - Flagstaff, Arizona 200 to 300 rooftop solar photovoltaic systems on single feeder1.5 to 2 MW of distributed generation4 weather stations in connected substations APS' innovative pilot project encourages distributed renewable resources, integrated with smart grid technology.

Solana: A "Sunny Place" 280-MW concentrating solar trough 30-year PPA for all output (~900 GWh/year)Planned commercial operation in 2013Near existing transmission lines70 miles southwest of PhoenixThermal storage capability with summer on-peak capacity factor over 90%To be built, owned and operated by Abengoa Solar Solana will generate enough clean, renewable electricity to meet the needs of about 70,000 Arizona homes.

Renewable Contracts Provide Bridge COD/ Fuel / Contract Location Developer/ Operator Status * PPA Signed Expected COD Term (years) Capacity (MW) Solar Solana (CSP Trough) Gila Bend, AZ Abengoa AD Feb-2008 2013 30 280 Total Solar 280 Wind Aragonne Mesa Santa Rosa, NM Bluearc Mgmt. Group IO Dec-2005 Dec-2006 20 90 High Lonesome Mountainair, NM Edison Mission Energy IO Feb-2008 Jul-2009 30 100 Total Wind 289 Geothermal CE Turbo - Salton Sea Imperial County, CA CalEnergy IO Jan-2006 Jan-2006 23 10 Total Geothermal 10 Biomass Snowflake Snowflake, AZ Renegy Holdings IO Jun-2008 Apr-2008 15 15 Total Biomass 15 Biogas Glendale Landfill Project Glendale, AZ Glendale Energy LLC UC Jul-2008 Dec-2009 20 3 Total Biogas 3 Total Renewable Contracted Capacity 597 As of July 23, 2010. * Advanced Development (AD), Under Construction (UC), or In Operation (IO). Perrin Ranch Williams, AZ NextEra Energy AD Jul- 2010 2012 25 99

APS Energy Efficiency Initiatives Increasing '05 '06 '07 '08 '09 '10 '11 '12 19 102 311 565 797 1117 1517 2007 Program costs currently recovered through retail DSM adjustorDecoupling or other financial mechanism under considerationUnder retail regulatory settlement, APS to achieve additional retail sales savings of 3.75% in 2010-2012Arizona energy efficiency rules require cumulative savings of 22% of retail sales by 2020 Cumulative Annual Energy Savings Associated with EE/DSM Programs APS will double customers' energy efficiency savings over the next three years. GWh

Highest Rating (AAA) and Ranked #2 Electric Utility Environmental, Sustainability and Technology Leadership Dow Jones Sustainability Index Global 100 Most Sustainable Corporations in World Social Responsibility Index "Best in Class" Distinction Social Responsibility Reporting Highest Overall Score of U.S. Utilities DOE/EPA Sustained Excellence Award Top 10 Utility Solar Ranking Top 10 in U.S. in Technology Innovation and #1 Utility Edison Electric Institute's 2008 Top Industry Award (Technical Innovation) We have been recognized internationally for our achievements.