AbstractBiohythane production from co-digestion of palm oil mill effluent (POME) with empty fruit bunches (EFB) and decanter cake (DC) by two-stage solid state anaerobic digestion process was investigated. The first stage, thermophilic hydrogen fermentation of co-digestion of POME with DC at 10, 30, 50 and 70% of DC in POME has hydrogen yield of 16, 14, 3 and 1ml H2/gVS, respectively. Co-digestion of POME with 10% DC gave the best hydrogen yield of 16ml H2/gVS with hydrogen production of 1.4 m3/ton mixed waste. Co-digestion of POME with 10% EFB gave the best hydrogen yield of 16ml H2/gVS with hydrogen production of 1.4 m3/ton mixed waste. The effluent from the hydrogen production was further converted to methane in the second stage. The methane yield from POME mixed withn10% DC was 391 mlCH4/gVS and from POME mixed with 10% EFB was 240 mlCH4/gVS. The hydrogen and methane content in biogas was 25.33% and 65.21% respectively. The two-stage solid stage anaerobic digestion process can be removal efficiently of cellulose 57-59%, hemicelluloses 35-40% and lignin 16-27%. Result obtained make practical use for the development of two-stage anaerobic digestion process providing hydrogen and methane co-production from palm oil waste residues.