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Nomenclature and registration services

Partner with CAS to get accurate and reliable chemical substance information, including CAS Registry Numbers®, CA Index Names, and other substance data.

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CAS Registry lookup

Find CA Index Names or CAS Registry Numbers for known substances using an exact computer match.

For exact matches of a substance with a CA Index Name or CAS Registry Number, complete and submit the CAS Registry Lookup Service Order Form. Turnaround time is 24 hours, excluding weekends and holidays, and the pricing is $65 per item searched.

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Chemist consultation

Get a new CAS Registry Number assigned by providing a substance name, chemical structure, process description, sequence, or other identifier, and our chemists will find or create a CAS Index Name or CAS Registry Number.

  1. To avoid delays, review the CAS Registration Criteria Overview and Registry Number Info Requirements before submitting your request.
  2. To expedite processing, submit the Chemist Consultation Order Form and relevant chemical structure diagram/descriptive information to answers@cas.org

    Note: A unique substance identifier is requested for each substance to facilitate matching the results to your input information. These identifiers can include internal substance IDs, such as tradename, product code, or sequential numbering.
  3. After submitting required information to CAS, our team of experienced chemists will evaluate your submission and provide you with the following substance information:
    - CAS Registry Numbers (new or existing)
    - CA Index Names (new or existing)
    - Substance definitions

Additional information can be found in our FAQ.


CAS service professionals are available to answer questions and help you with requests.

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+1 614.447.3870 (Outside North America)