Chemoselective hydrolysis of heterocyclic nitriles can be achieved by an easy to use immobilized biocatalyst prepared from Rhodococcus sp. Pyrimidine‐2‐carbonitrile (2a) and 3‐chloropyridazine‐4‐carbonitrile (4a) were converted into the corresponding amides while from 2‐ethoxycarbonyl‐4‐pyridinecarbonitrile (1a), 6‐methylpyridazine‐3‐carbonitrile (3a), 3‐chloropyridazine‐4‐carbonitrile (4a), 3‐ethoxycarbonyl‐4,5‐dihydroisoxazole‐5‐carbonitrile (8a), indole‐3‐carbonitrile (9a) and indole‐3‐ylacetonitrile (10a) the acids were formed.