### 16.6. Does InChI require all atoms including hydrogens in the input? 

Having explicit hydrogen atoms in the input is desirable. 

Anyway, InChI Software assumes that the input structure may contain implicit hydrogen atoms and – if they are detected – will add hydrogen atoms to eligible atoms to satisfy an element’s standard valences.

However, be warned that this may not be a 100%-reliable procedure, especially for organometallics.