CAS REGISTRY®, the CAS substance collection, is the premier source relied upon by scientists and regulators worldwide for accurate information on chemical substances.

CAS Registry Numbers (CAS RN) are simple and regular, convenient for database searches. They offer a reliable, common and international link to every specific substance across the various …

“CAS registry” is a registered trademark of the American Chemical society.

Quickly confirm chemical names, CAS Registry Numbers®, structures or basic physical properties by searching compounds of general interest or leveraging an API connection.

Oct 8, 2024 · What is a CAS Number? A CAS number is a unique identifier assigned to every chemical substance described in the open scientific literature. This number, typically comprising up to ten …

Dec 16, 2025 · You can also identify your substance of interest by its CAS Registry Number®, which is universally used to provide a unique, unmistakable identifier for chemical substances.

Chemical Abstracts Service (CAS), a division of the American Chemical Society, assigns these identifiers to every chemical that has been described in the literature.