In the present study the catalytic steam gasification of biomass to produce hydrogen-rich gas with calcined dolomite as catalyst in an externally heated fixed bed reactor was investigated. The influence of the reactor temperature on yield and product composition was studied at the temperature range of 700°C–900°C. Over the ranges of experimental conditions examined, tar was completely decomposed as temperature increases from 800°C to 900°C. Higher temperature resulted in more H2 and CO₂ production, and dry gas yield. The highest H₂ content of 51.02 V%, and the highest H₂ yield of 1.66 m³/kg biomass were observed at the highest temperature level of 900°C.