In case of gaseous reduction of iron oxide pellets, the overall reaction rate is usually determined by the resistance of the three processes of diffusion within the gas film at the boundary, gas diffusion within the particle and the rate of chemical reaction at the reaction interface. Among these, the resistance due to diffusion at the boundary film can be made negligible by making a sufficient supply of gas current; but the other two cannot be ignored. The authors suggest a method of analysis in which the coefficient of diffusion within the particle and the coefficient of reaction rate at 50% and 87.5% reduction ratio, can be determined by a simple method using the calculation chart prepared taking into consideration even the adsorption of water. Here it is reported that this method gives good results in case of low temperature (500 degrees, 550 degrees C) hydrogen reduction of Brazilian iron ore pellets using the data obtained by thermo-balance.