A study on pyrolysis of palm oil wastes in a countercurrent fixed bed was carried out, aiming to characterize the hydrogen rich gas products in view of enhanced energy recycling. The effects of temperature, residence time and catalyst adding on the yields and distribution of hydrogen rich gas products were investigated. The main gas species generated, as identified by Micro-GC, were H-2, CO, CO2, CH4 and trace amounts of C2H4 and C2H6. With temperature increasing from 500 C to 900 C, the total gas yield was enhanced greatly and reached the maximum value (similar to 70 wt.%, on the raw biomass sample basis) at 900 C with big portions of H-2 (33.49 vol.%) and CO (41.33 vol.%). Residence time showed a significant influence on the upgrading of H-2 and CO2 yields. The optimum residence time (9 s) was found to get a higher H2 yield (10.40 g/kg (daf)). The effect of adding chemicals (Ni, gamma-Al2O3, Fe2O3 and La/Al2O3, etc.) on gas product yield was investigated and adding Ni showed the greatest catalytic effect with the maximum H-2 yield achieved at 29.78 g/kg (daf). (c) 2006 Elsevier B.V. All rights reserved.