QuickLinks -- Click here to rapidly navigate through this document

Exhibit 99.3

PRO FORMA FINANCIAL INFORMATION OF ISONICS CORPORATION AND
ENCOMPASS MATERIALS GROUP LIMITED

Unaudited Pro Forma Combined Balance Sheet as of April 30, 2004

Notes to Unaudited Pro Forma Combined Balance Sheet as of April 30, 2004

Unaudited Pro Forma Combined Statement of Operations for the year ended April 30, 2004

Notes to Unaudited Pro Forma Combined Statement of Operations for the year ended April 30, 2004

UNAUDITED PRO FORMA COMBINED FINANCIAL INFORMATION
(Dollars in thousands)

        The following unaudited pro forma financial information of Isonics Corporation gives effect to the acquisition of the business and assets of Encompass Materials Group Limited ("EMG") as if such transaction was consummated April 30, 2004, in the case of the Unaudited Pro Forma Combined Balance Sheet and as if such transaction was consummated on May 1, 2003, in the case of the Unaudited Pro Forma Combined Statement of Operations for the year ended April 30, 2004. The Unaudited Pro Forma Combined Balance Sheet as of April 30, 2004 includes EMG historical information as of March 31, 2004. The Unaudited Pro Forma Combined Statement of Operations for the year ended April 30, 2004 includes EMG historical information for the year ended March 31, 2004. The acquisition of the business and assets of EMG was completed on June 11, 2004. All related adjustments are described in the accompanying notes. In the opinion of management, all adjustments have been made that are necessary to present fairly the pro forma data.

        The following unaudited pro forma combined financial information is presented for illustrative purposes only, does not purport to be indicative of our financial position or results of operations as of the date hereof, or as of or for any other future date, and is not necessarily indicative of what our actual financial position or results of operations would have been had the foregoing transaction been consummated on such dates, nor does it give effect to (i) any transactions other than the foregoing transaction and those described in the accompanying Notes to Unaudited Pro Forma Combined Financial Information or (ii) Isonics Corporation or EMG's results of operations since April 30, 2004. The following unaudited pro forma combined financial information does not give effect to any anticipated annual savings or the additional revenues expected to be achieved following the consummation of the transaction. Actual amounts could differ from those presented.

        The following unaudited pro forma combined financial information is based upon the historical financial statements of Isonics Corporation and EMG, and should be read in conjunction with such historical financial statements, the related notes and the Notes to Unaudited Pro Forma Combined Financial Information.

        In the preparation of the unaudited pro forma combined financial information, management has estimated that the historical book value of the EMG assets and liabilities acquired approximates the fair value thereof, except for property and equipment which has been estimated based upon preliminary appraisal results as described in the Notes to Unaudited Pro Forma Combined Financial Information. Although the final appraisal and purchase accounting allocation is not anticipated to result in values that are materially greater or less than the values assumed in the preparation of the following unaudited pro forma combined financial information, there can be no assurance with respect thereof.

2

ISONICS CORPORATION

UNAUDITED PRO FORMA COMBINED BALANCE SHEET

APRIL 30, 2004

(Dollars in thousands)

ASSETS

			Isonics Historical		EMG Historical		Pro Forma Adjustments			Pro Forma Combined
CURRENT ASSETS
	Cash and cash equivalents		$	3,691	$	9	$	(415	)(1)(4)	$	3,285
	Accounts receivable			851		279		—			1,130
	Inventories			985		347		—			1,332
	Prepaid expenses and other current assets			143		73		—			216
		Total current assets		5,670		708		(415	)		5,963
LONG-TERM ASSETS
	Property and equipment, net			471		648		1,948	(1)		3,067
	Goodwill			1,807		—		470	(1)		2,277
	Intangible assets, net			706		—		—			706
	Other assets			27		16		—			43
		Total long-term assets		3,011		664		2,418			6,093
TOTAL ASSETS			$	8,681	$	1,372	$	2,003		$	12,056

LIABILTIES AND STOCKHOLDERS' EQUITY

			Isonics Historical		EMG Historical			Pro Forma Adjustments			Pro Forma Combined
CURRENT LIABILITIES
	Line of credit		$	—	$	133		$	(133	)(4)	$	—
	Notes payable			—		233			(233	)(4)		—
	Notes payable—Silver Silicon Ltd.			—		—			1,700	(1)		1,700
	Current portion of obligation under capital leases			54		—			—			54
	Accounts payable			628		338			—			966
	Accrued liabilities			256		166			—			422
	Due to related party			—		128			(128	)(2)		—
		Total current liabilities		938		998			1,206			3,142
	Obligation under capital leases, net of current portion			32		—			—			32
	Notes payable—shareholders			—		2,262			(2,262	)(2)		—
TOTAL LIABILITIES				970		3,260			(1,056	)		3,174
STOCKHOLDERS' EQUITY (DEFICIT)				7,711		(1,888	)		3,059	(1)(3)		8,882
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY			$	8,681	$	1,372		$	2,003		$	12,056

3

ISONICS CORPORATION

NOTES TO UNAUDITED PRO FORMA COMBINED BALANCE SHEET

APRIL 30, 2004

(Dollars in Thousands)

(1)

The aggregate purchase price paid by Isonics Corporation and the related purchase accounting (which is based upon preliminary appraisal results) for the acquisition, assuming it was consummated at April 30, 2004 is as follows:

Calculation of purchase price

Note payable to Silver Silicon Ltd. (formerly EMG)	$	1,700
731,930 shares of common stock (valued at the closing price of our common stock on June 11, 2004) issued to Silver Silicon Ltd.		1,171
Estimated legal, accounting and other advisory fees		49
		2,920

Fair value of net assets acquired

Working capital	$	(162	)
Other long-term assets		16
Property and equipment (based upon preliminary appraisal results)		2,596
Goodwill		470
	$	2,920

(2)

Represents excluded liabilities that remain with the Silver Silicon Ltd.

(3)

Elimination of EMG equity of ($1,888).

(4)

Line of credit and notes payable totaling $366 paid off by Isonics at closing per the terms of the agreement.

4

ISONICS CORPORATION

UNAUDITED PRO FORMA COMBINED STATEMENT OF OPERATIONS

YEAR ENDED APRIL 30, 2004

(Dollars in thousands, except per share amounts)

			Isonics Historical			EMG Historical			Pro Forma Adjustments			Pro Forma Combined
Revenues			$	8,721		$	3,539		$	—		$	12,260
Cost of revenues				7,138			4,403			389	(4)		11,930
		Gross margin		1,583			(864	)		(389	)		330
Operating expenses:
	Selling, general and administrative			5,186			668			—			5,854
	Research and development			569			—			—			569
		Total operating expenses		5,755			668			—			6,423
Operating loss				(4,172	)		(1,532	)		(389	)		(6,093	)
Other income (expense), net				9			(211	)		116	(2)(3)		(86	)
Loss from continuing operations before income taxes				(4,163	)		(1,743	)		(273	)		(6,179	)
Income taxes				—			—			—			—
Loss from continuing operations				(4,163	)		(1,743	)		(273	)		(6,179	)
Loss from discontinued operations				—			(79	)		79	(1)		—
Gain on disposal of discontinued operations				—			142			(142	)(1)		—
NET LOSS			$	(4,163	)	$	(1,680	)	$	(336	)	$	(6,179	)
DEEMED DIVIDENDS ON PREFERRED STOCK			$	(2,862	)		—			—		$	(2,862	)
NET LOSS ATTRIBUTABLE TO COMMON STOCKHOLDERS			$	(7,025	)	$	(1,680	)	$	(336	)	$	(9,041	)
Net loss per share—basic and diluted
	Net loss per share attributable to common stockholders		$	(.53	)		—			—		$	(.65	)
	Shares used in computing per share information			13,252			—			732			13,984

5

ISONICS CORPORATION

NOTES TO UNAUDITED PRO FORMA COMBINED STATEMENT OF OPERATIONS

April 30, 2004

(Dollars in Thousands)

(1)

Eliminates discontinued operations associated with Encompass Distribution Services, LLC.

(2)

Eliminates interest expense of $211 associated with EMG debt and payables to related parties.

(3)

Adds interest expense ($95) associated with $1,700 payable to Silver Silicon Ltd. at 6% (payable ratably over 33 months beginning October 2004).

(4)

Additional depreciation expense associated with allocation of excess purchase price to property and equipment over the recorded book value. Allocation was assumed to have a five-year life for depreciation purposes.

6

QuickLinks

PRO FORMA FINANCIAL INFORMATION OF ISONICS CORPORATION AND ENCOMPASS MATERIALS GROUP LIMITED