Abstract The transformation of crude peat (peat in its natural aqueous medium) has been studied under hydrogenolysis conditions using CO and H 2 mixtures as reducing agent. Batch autoclave experiments were conducted with a moderately humified peat at reaction temperatures up to 400°C. Micropetrological and chemical studies on untreated and treated peat as well as on THF extracted residues show that the different organic components present in peat undergo changes very similar to those observed during coal liquefaction. Liptinitic components are rapidly converted and do not appear in the unconverted residues above 275°C. The huminitic components regularly increase their reflectivity and appear to have been coalified to the stage of subbituminous coal A, from that point on being the major contributors to the newly formed vitroplast. The latter is observed for the first time following the hydrogenolysis treatment at 300°C. Beyond this temperature the vitroplast undergoes severe alterations becoming a bitumen-like material. In the presence of anthracene oil as organic carrier solvent, the hydrogenolysis reactions using CO and H 2 result in the formation of mesophase at temperatures as low as 380°C. Coke-like structures can thus be formed from peat.