Simultaneous gasification and steam reforming of t he biomass on Ni/dolomite catalyst in fluidized bed reactor were studied in the gaseous p roduction in the one stage reactor. Problem statement: The parameters such as temperature, steam flow rat e, biomass feed rate, gas flow rate for fluidization, oxygen flow rate and catalyst types w ere studied to produce the high gaseous products including tar elimination. Approach: The temperature at 780°C, steam flow rate of 222 mmoL h -1 , gas flow rate for fluidization 450 mL min -1 and oxygen input 50 mL min -1 were found to be the suitable conditions. The Ni/Dolomite and the developed Ni/Dolomite were studied about their performance. Results: It was confirmed that Ni/Dolomite and newly developed Ni-WO 3/Dolomite show high performance in biomass gasification. Conclusion/Recommendations: It was claimed that Ni/Dolomite catalyst was the effective and give bes t performance for tar cracking. Newly developed Ni-WO 3/Dolomite catalyst was investigated to resist sulfu r nd coking. Three types of catalyst were used in the biomass gasification, which are Ni/Dolo mite, Ni/Dolomite+Silica binder and Ni- WO 3/Dolomite. From the XRD analysis, structures of typ e 1 (Ni/dolomite) and type 2 (Ni/Dolomite+Silica binder) were similar which were in CaCO 3, MgNiO 2, NiO and MgO forms. Type 3 (Ni-WO 3/Dolomite) was CaWO 4, MgNiO 2, NiO and MgO forms. When the catalytic gasification was operated, newly Ni- WO 3/Dolomite catalyst was the best catalyst for bamboo and palm shell biomasses, which could produce the high carbon monoxide and hydrogen but low methane and carbon dioxide were found. Carbon deposition on catalyst was around 0.37 mg according to the TG analysis.