What are InChI and InChIKey?

InChI, short for International Chemical Identifier, is a textual identifier for molecules developed by the International Union of Pure and Applied Chemistry (IUPAC) and National Institute of Standards and Technology (NIST).

Examples of InChI presentation of molecules:

Aspirin: 1S/C9H8O4/c1-6(10)13-8-5-3-2-4-7(8)9(11)12/h2-5H,1H3,(H,11,12)
Nitrobenzene: 1S/C6H5NO2/c8-7(9)6-4-2-1-3-5-6/h1-5H
Nicotine: 1S/C10H14N2/c1-12-7-3-5-10(12)9-4-2-6-11-8-9/h2,4,6,8,10H,3,5,7H2,1H3/t10-/m0/s1
Thiamine: 1S/C12H17N4OS/c1-8-11(3-4-17)18-7-16(8)6-10-5-14-9(2)15-12(10)13/h5,7,17H,3-4,6H2,1-2H3,(H2,13,14,15)/q+1

InChIKey is a fixed length of 27 characters representation of the InChI. Examples of InChIKey presentation of molecules:

Aspirin: BSYNRYMUTXBXSQ-UHFFFAOYSA-N
Nitrobenzene: LQNUZADURLCDLV-UHFFFAOYSA-N
Nicotine: SNICXCGAKADSCV-JTQLQIEISA-N
Thiamine: JZRWCGZRTZMZEH-UHFFFAOYSA-N

For more information, see "International Chemical Identifier" at wikipedia.org.

You can use our "Search Molecule by InChIKey" tool to search for the molecule with any given InChIKey.

⇒ Search Molecule by InChIKey

⇐ SMILES (Simplified Molecular Input Line Entry Specification)

⇑ Molecule Presentation and Identification

⇑⇑ Molecule FAQ