In this study, the steam reforming of tar was catalyzed by dolomite, Ni/dolomite, and Ni/CeO2 for syngas production under different reaction temperature and weight hourly space velocity (WHSV, h(-1)). The tar was the major side product from the biomass gasification. Current results revealed that the nickel doped catalyst on dolomite with CO2 in the feed stream yielded the highest H-2 and syngas production among all reaction conditions. Comparing to the use of dolomite, when Ni-dolomites was used as catalyst, the yield of H-2 increased by 33%, the yield of syngas increased by 7%, and the yield of CH4 decreased by 59%. It was also found that the yield of syngas, H-2, or CO under the Nil dolomite catalyst were significant higher (p < 0.001) than those under the dolomite catalyst using analysis of covariance. Taguchi method was also applied to elucidate the sensitivity of experimental condition in this study. The impact of the factors on the entire performance had the following order: types of the catalyst > CO2 concentration in the feed stream > reaction temperature > weight hourly space velocity. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.