CAS Registry Services℠
Gain clarity with unique identifiers of chemical substances
CAS Registry Services helps you obtain CAS Registry Numbers® (CAS RNs®), CA Index Names, and substance information for reports, proprietary files, online searching, and regulatory applications.
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![A digital card displaying information about the element nitrogen from the periodic table. It includes the atomic number 7, atomic mass range [14.00643, 14.00728], symbol 'N', and electron configuration [He]2s²2p³. A blue box with white text shows the CAS registry number 7727-37-9.](https://cdn.prod.website-files.com/650861f00f97fe8153979335/68557701f77e4a8e679046f9_d838e484db6befacc157d5154308fe6d_what-is-reg-number.svg)
Looking for CAS Registry Numbers or CA Index Names for known substances?
If you’re looking for a unique substance, simply complete and submit a CAS Registry Lookup service order form and receive results within 24 hours (excluding weekends and holidays). The current cost is $70 per substance name or CAS Registry Number searched.
Also available is CAS Common Chemistry, an open community resource with nearly 500,000 chemical substances from CAS REGISTRY®.