The goal of this study is to experimentally evaluate the effects of different types of catalysts, GHSV (Gas Hourly Space Velocity) and O<SUB>2</SUB>/C ratio of reactants on the performance of a methane reformer, which was designed and built to produce syngas in the laboratory. Two different types of catalysts were employed ?a precious metal catalyst (monolith type) consisting of 1wt% Rh/CeO<SUB>2</SUB>-ZrO<SUB>2</SUB> and a mixed catalyst consisting of 1wt% Rh/CeO<SUB>2</SUB>-ZrO<SUB>2</SUB> (monolith type) and 18wt% Ni on calcium aluminate catalyst (pellet type). The O<SUB>2</SUB>/C ratio of reactants was varied from 0.25 to 1.0 and GHSV was ranged from 5,000h<SUP>-1</SUP> to 10,000h<SUP>-1</SUP>. For each experimental condition, the catalyst temperature (the temperature of the reaction mixture) and concentrations of product gases (H<SUB>2</SUB>, CO, CO<SUB>2</SUB>) were measured. The results showed that both catalyst temperature and syngas concentration were increased as GHSV increased up to 10,000h<SUP>-1</SUP>, and the precious metal catalyst showed the better performance than the mixed catalyst. However, performance of the reformer was deteriorated when the O<SUB>2</SUB>/C ratio was increased above 0.75.