The production of aliphatic and aromatic aldehydes by oxidation of primary alcohols was achieved with Gluconobacter oxydans DSM 2343. The biotransformation was optimised studying the oxidation of 2-phenyl-1-ethanol to 2-phenylacetaldehyde. A high molar conversion (95% chromatographic conversion, 83% of isolated yield) was obtained using cells grown on glycerol as the main carbon source and directly used in the cultural medium after 24 h at 28degreesC, pH 4.5 and 5 g L-1 substrate concentration. The conversion of structurally different primary alcohols was performed under these conditions allowing the chemoselective production of aldehydes, sometimes with very good yields. (C) 2002 Published by Elsevier Science Ltd.