CAS Registry Number (CAS RN) Verified Partner Program

The CAS Registry Number® (CAS RN®) is a unique identifier that provides an unambiguous means to distinguish chemical substances or molecular structures when there are many possible systematic, generic, proprietary or otherwise trivial names.  CAS RNs are widely used as an authoritative global industry standard to ensure the accuracy of chemical information.

CAS Registry Number Verified Partner Program

A CAS Registry Number license is required anytime an organization will “publish” CAS Registry Numbers to the public or use them to support features of a platform that is publicly or commercially available (i.e., as a “search by CAS RN” feature), even if the CAS Registry Number is not displayed as part of the answer.  (Note:  Private use of CAS RNs, for example an internal company tracking system, does not require licensing.)

Proper use of the CAS registered trademark names are:

  • CAS Registry Number®
  • CAS RN®

Improper use includes, but is not limited to:

  • CAS No.
  • CAS #
  • Registry # / Reg #

If you use CAS RNs publicly, take advantage of this worthwhile opportunity to ensure you are contributing to the accuracy and safety of chemical information.  To determine your organization’s licensing requirements, contact the CAS Customer Center to discuss your needs.