To perform the linear regression analysis of the powder reaction rate, some kinetic equations are derived on the basis of the Hao and Tanaka＇s concentric spherical model (Intern. Chem. Eng. 30, 244 (1990) and Can. J. Chem. Eng. 68, 81 (1990)) assuming monodisperse particles. The applicability of the kinetic equations is examined by using the experimental data of both counterdiffusion system and uni-directional diffusion system. This linear regression analysis enables us to decide rapidly about the suitability of the model, to predict the diffusion mode and to determine the diffusivity.