The kinetics of the methane steam reforming reaction over an industrial catalyst(ICI 57-4M) was investigated at emperatures 550-650℃ and at total pressures 1-5atm in a flow reactor. The experiments were performed by varying the inlet partial pressure of methane, hydrogen, and water. Depending on hydro-gen partial pressures and reaction temperatures, the following two rate equations, one with the hydrogen inhibition effects and the othe without the effects, were given: -r=2.4×10¹¹ exp(-45300/RT) [P₅-(P₃+P₄)(1-X_e)/X_e]/P₁ -r=2.3×10⁸ exp(-32000/RT) [P₅-(P₃+P₄)(1-X_e)/X_e] The hydrogen inhibition effect was observed at high hydrogen partial pressures, and with increasing reaction temperature, the hydrogen partial pressure above which the inhibition effect became significant has increased. Depending on the rate expressions chosen for the analysis of the data, it was also shown that the activation energies and the interpretation on the role of the reactant species involved could be widely different.