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                       SECURITIES AND EXCHANGE COMMISSION


                             WASHINGTON, D.C. 20549



                                    FORM 8-A

                FOR REGISTRATION OF CERTAIN CLASSES OF SECURITIES
                     PURSUANT TO SECTION 12(b) OR (g) OF THE
                         SECURITIES EXCHANGE ACT OF 1934



                                  ISOMEDIX INC.
             (Exact name of registrant as specified in its charter)



            Delaware                                      22-1986189
    (State of incorporation                            (I.R.S. Employer
       or organization)                               Identification No.)



            11 Apollo Drive
          Whippany, New Jersey                               07981
(Address of principal executive offices)                   (Zip Code)


                                               
If this Form relates to the registration of a     If this Form relates to the registration of a     
class of debt securities and is effective upon    class of debt securities and is to become         
filing pursuant to General Instruction A(c)(1)    effective simultaneously with the effectiveness of
please check the following box. [ ]               a concurrent registration statement under the     
                                                  Securities Act of 1933 pursuant to General        
                                                  Instruction A(c)(2) please check the following    
                                                  box. [ ]                                          



Securities to be registered pursuant to Section 12(b) of the Act:

Title of Each Class                       Name of Each Exchange on Which
to be so Registered                       Each Class is to be Registered

Series A Preferred Stock,                  New York Stock Exchange, Inc.
$1.00 par value, and
Preferred Stock Purchase Rights


       Securities to be registered pursuant to Section 12(g) of the Act:

                                      None







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                 INFORMATION REQUIRED IN REGISTRATION STATEMENT


Item 1.     Description of Securities to be Registered.

            On June 10, 1988, the Board of Directors of Isomedix Inc. (the
"Company") declared a dividend of one preferred share purchase right (a "Right")
for each outstanding share of common stock, $.01 par value (the "Common
Shares"), of the Company. The dividend was paid on June 21, 1988 (the "Record
Date") to the stockholders of record on that date. Each Right entitles the
registered holder to purchase from the Company one one-hundredth of a share of
Series A Preferred Stock, $1.00 par value (the "Preferred Shares"), of the
Company, at a price of $20.00 per one one-hundredth of a Preferred Share (the
"Purchase Price"), subject to adjustment. The description and terms of the
Rights are set forth in a Rights Agreement (the "Rights Agreement") between the
Company and Midlantic National Bank, as Rights Agent (the "Rights Agent").

            Until the earlier to occur of (i) 10 days following a public
announcement that a person or group of affiliated or associated persons (an
"Acquiring Person") have acquired beneficial ownership of 20% or more of the
outstanding Common Shares or (ii) 10 business days (or such later date as may be
determined by action of the Board of Directors prior to such time as any person
becomes an Acquiring Person) following the commencement of, or announcement of
an intention to make, a tender offer or exchange offer the consummation of which
would result in the beneficial ownership by a person or group of 20% or more of
such outstanding Common Shares (the earlier of such dates being called the
"Distribution Date"), the Rights will be evidenced, with respect to any of the
Common Share certificates outstanding as of the Record Date, by such Common
Share certificate with a copy of a "Summary of Rights" document attached
thereto.

            The Rights Agreement provides that, until the Distribution Date, the
Rights will be transferred with and only with the Common Shares. Until the
Distribution Date (or earlier redemption or expiration of the Rights), new
Common Share certificates issued after the Record Date, upon transfer or new
issuance of Common Shares will contain a notation incorporating the Rights
Agreement by reference. Until the Distribution Date (or earlier redemption or
expiration of the Rights), the surrender for transfer of any certificates for
Common Shares, outstanding as of the Record Date, even without such notation or
a copy of the Summary of Rights document being attached thereto, will also
constitute the transfer of the Rights associated with



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the Common Shares represented by such certificate. As soon as practicable
following the Distribution Date, separate certificates evidencing the Rights
("Rights Certificates") will be mailed to holders of record of the Common Shares
as of the close of business on the Distribution Date and such separate Rights
Certificates alone will evidence the Rights.

            The Rights are not exercisable until the Distribution Date. The
Rights will expire on June 10, 1998 (the "Final Expiration Date"), unless the
Final Expiration Date is extended or unless the Rights are earlier redeemed by
the Company, in each case, as described below.

            The Purchase Price payable, and the number of Preferred Shares or
other securities or property issuable, upon exercise of the Rights are subject
to adjustment from time to time to prevent dilution (i) in the event of a stock
dividend on, or a subdivision, combination or reclassification of, the Preferred
Shares, (ii) upon the grant to holders of the Preferred Shares of certain rights
or warrants to subscribe for or purchase Preferred Shares at a price, or
securities convertible into Preferred Shares with a conversion price, less than
the then current market price of the Preferred Shares or (iii) upon the
distribution to holders of the Preferred Shares of evidences of indebtedness or
assets (excluding regular periodic cash dividends paid out of earnings or
retained earnings or dividends payable in Preferred Shares) or of subscription
rights or warrants (other than those referred to above).

            The number of outstanding Rights and the number of one
one-hundredths of a Preferred Share issuable upon exercise of each Right are
also subject to adjustment in the event of a stock split of the Common Shares or
a stock dividend on the Common Shares payable in Common Shares or subdivisions,
consolidations or combinations of the Common Shares occurring, in any such case,
prior to the Distribution Date.

            Preferred Shares purchasable upon exercise of the Rights will not be
redeemable. Each Preferred Share will be entitled to a minimum preferential
quarterly dividend payment of $1.00 per share but will be entitled to an
aggregate dividend of 100 times the dividend declared per Common Share. In the
event of liquidation, the holders of the Preferred Shares will be entitled to a
minimum preferential liquidation payment of $100 per share but will be entitled
to an aggregate payment of 100 times the payment made per Common Share. Each
Preferred Share will have 100 votes, voting together with the Common Shares.
Finally, in the event of any merger, consolidation or other



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transaction in which Common Shares are exchanged, each Preferred Share will be
entitled to receive 100 times the amount received per Common share. These rights
are protected by customary antidilution provisions.

            Whenever quarterly dividends or other dividends or distributions
payable on the Preferred Shares are in arrears, thereafter and until all accrued
and unpaid dividends and distributions, whether or not declared, on Preferred
Shares outstanding shall have been paid in full, the Company shall not redeem or
purchase or otherwise acquire for consideration any Preferred Shares, or any
stock ranking on a parity with the Preferred Shares, except in accordance with a
purchase offer made in writing or by publication (as determined by the Board of
Directors) to all holders of such Preferred Shares upon such terms as the Board
of Directors, after consideration of the respective annual dividend rates and
other relative rights and preferences of the respective series and classes,
shall determine in good faith will result in fair and equitable treatment among
the respective series or classes.

            The Certificate of Incorporation of the Company shall not be amended
in any manner which would materially alter or change the powers, preferences or
special rights of the Preferred Shares so as to affect them adversely without
the affirmative vote of the holders of at least two-thirds of the outstanding
Preferred Shares, voting together as a single series.

            Because of the nature of the Preferred Shares' dividend, liquidation
and voting rights, the value of the one one-hundredth interest in a Preferred
Share purchasable upon exercise of each Right should approximate the value of
one Common Share.

            In the event that the Company is acquired in a merger or other
business combination transaction or 50% or more of its consolidated assets or
earning power are sold, proper provision will be made so that each holder of a
Right will thereafter have the right to receive, upon the exercise thereof at
the then current exercise price of the Right, that number of shares of common
stock of the acquiring company which at the time of such transaction will have a
market value of two times the exercise price of the Right. In the event that any
person becomes an Acquiring Person, proper provision shall be made so that each
holder of a Right, other than Rights beneficially owned by the Acquiring Person
(which will thereafter be void), will thereafter have the right to receive upon
exercise that number of Common



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Shares having a market value of two times the exercise price of the Right.

            At any time after the acquisition by a person or group of affiliated
or associated persons of beneficial ownership of 20% or more of the outstanding
Common Shares, the Board of Directors of the Company may exchange the Rights
(other than Rights owned by such person or group which have become void), in
whole or in part, at an exchange ratio of one Common Share, or one one-hundredth
of a Preferred Share (or of a share of a class or series of the Company's
preferred stock having equivalent rights, preferences and privileges), per Right
(subject to adjustment).

            With certain exceptions, no adjustment in the Purchase Price will be
required until cumulative adjustments require an adjustment of at least 1% in
such Purchase Price. No fractional Preferred Shares will be issued (other than
fractions which are integral multiples of one one-hundredth of a Preferred
Share, which may, at the election of the Company, be evidenced by depositary
receipts) and in lieu thereof, an adjustment in cash will be made based on the
market price of the Preferred Shares on the last trading day prior to the date
of exercise.

            At any time prior to the acquisition by a person or group of
affiliated or associated persons of beneficial ownership of 20% or more of the
outstanding Common Shares, the Board of Directors of the Company may redeem the
Rights in whole, but not in part, at a price of $.01 per Right (the "Redemption
Price"). The redemption of the Rights may be made effective at such time on such
basis and with such conditions as the Board of Directors in its sole discretion
may establish. In addition, if a bidder who does not beneficially own more than
1% of the Common Shares (and who has not within the past year owned in excess of
1% of the Common Shares and, at a time he held such greater than 1% stake,
disclosed, or caused the disclosure of, an intention which relates to or would
result in the acquisition or influence of control of the Company) proposes to
acquire all of the Common Shares (and all other shares of capital stock of the
Company entitled to vote with the Common Shares in the election of directors or
on mergers, consolidations, sales of all or substantially all of the Company's
assets, liquidation, dissolutions or windings up) for cash at a price which a
nationally recognized investment banker selected by such bidder states in
writing is fair, and such bidder has obtained written financing commitments (or
otherwise has financing) and complies with certain procedural requirements, then
the Company, upon the request of the bidder, will hold a special stockholders
meeting



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to vote on a resolution requesting the Board of Directors to accept the bidder's
proposal. If a majority of the outstanding shares entitled to vote on the
proposal vote in favor of such resolution, then for a period of 60 days after
such meeting the Rights will be automatically redeemed at the Redemption Price
immediately prior to the consummation of any tender offer for all of such shares
at a price per share in cash equal to or greater than the price offered by such
bidder; provided, however, that no redemption will be permitted or required
after the acquisition by any person or group of affiliated or associated persons
of beneficial ownership of 20% or more of the outstanding Common Shares.
Immediately upon any redemption of the Rights, the right to exercise the Rights
will terminate and the only right of the holders of Rights will be to receive
the Redemption Price.

            The terms of the Rights may be amended by the Board of Directors of
the Company without the consent of the holders of the Rights, including an
amendment to lower the threshold for exercisability of the Rights from 20% to
not less than the greater of (i) any percentage greater than the largest
percentage of the outstanding Common Shares then known to the Company to be
beneficially owned by any person or group of affiliated or associated persons
and (ii) 15%, except that from and after such time as any person becomes an
Acquiring Person no such amendment may adversely affect the interests of the
holders of the Rights.

            Until a Right is exercised, the holder thereof, as such, will have
no rights as a stockholder of the Company, including, without limitation, the
right to vote or to receive dividends.

            Article FOURTEENTH of the Company's Certificate of Incorporation
provides: (i) that certain business combinations involving the Company and any
beneficial owner of 20% or more of the outstanding voting securities of the
Company be approved by the holders of at least 80% of the Company's voting
securities, unless certain conditions, including a minimum price requirement,
are satisfied, or unless the Board of Directors by at least a majority vote of
all of its members had waived such conditions or had approved, prior to the time
such person became a 20% beneficial owner, the acquisition of such 20%
beneficial ownership position or the proposed business combination, (ii) that
any action taken by the Company's shareholders be taken at an annual or special
meeting held upon prior notice and pursuant to a vote (in addition, the
Company's By-laws contain a provision the effect of which is to prohibit the
shareholders of the Company from calling a special meeting without the approval
of the Board of Directors, thereby preventing shareholders, without



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such approval, from initiating action other than at the Annual Meeting of
Shareholders), except that holders of any of the Company's preferred stock may
act by written consent under certain circumstances as provided in Article FOURTH
of the Company's Certificate of Incorporation and (iii) the vote of not less
than 80% of the Company's outstanding voting securities are required to repeal,
alter or amend the Company's By-laws, any of the provisions described above and
the provisions in the Company's Certificate of Incorporation with respect to the
division of the Board of Directors into classes.

            This summary description of the Rights is qualified in its entirety
by reference to the Rights Agreement, which is hereby incorporated herein by
reference.

            The Rights have certain anti-takeover effects. The Rights will cause
substantial dilution to a person or group that attempts to acquire the Company
on terms not approved by the Company's Board of Directors, except pursuant to an
offer conditioned on a substantial number of Rights being acquired. The Rights
should not interfere with any merger or other business combination approved by
the Board of Directors since the Rights may be redeemed by the Company at $.01
per Right prior to the time that a person or group has acquired beneficial
ownership of 20% or more of the Common Shares.

            The Rights Agreement, dated as of June 10, 1988, between the Company
and Midlantic National Bank, as Rights Agent, specifying the terms of the
Rights, and the Certificate of Designation setting forth the terms of the
Preferred Shares are attached hereto as exhibits and are incorporated herein by
reference. The foregoing description of the Rights is qualified by reference to
such exhibits.





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Item 2.     Exhibits.

            1.    Rights Agreement dated as of June 10, 1988 between Isomedix
                  Inc. and Midlantic National Bank which includes the form of
                  Certificate of Designation setting forth the terms of the
                  Series A Preferred Stock, par value $1.00 per share, as
                  Exhibit A, the form of Rights Certificate as Exhibit B and the
                  Summary of Rights to Purchase Preferred Shares as Exhibit C
                  (incorporated by reference to Exhibit 4(k) to the Registrant's
                  Annual Report on Form 10-K for the fiscal year ended December
                  31, 1994).

            2.    Certificate of Incorporation of the Company, as amended, and
                  Certificate of Designation of Series A Preferred Stock, par
                  value $1.00 per share (incorporated by reference to Exhibit
                  3(a) to the Registrant's Annual Report on Form 10-K for the
                  fiscal year ended December 31, 1994).

            3.    Specimen Certificate of Series A Preferred Stock, $1.00 par
                  value; to be filed by amendment under cover of Form 8 prior to
                  the issuance of any of such Series A Preferred Stock.




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                                    SIGNATURE


            Pursuant to the requirements of Section 12 of the Securities
Exchange Act of 1934, the registrant has duly caused this registration statement
to be signed on its behalf by the undersigned, thereto duly authorized.

Dated:  May 5, 1997


                                          ISOMEDIX INC.


                                          By /s/ Thomas J. DeAngelo
                                             ----------------------
                                             Thomas J. DeAngelo
                                             Vice President-Finance
                                               and Administration