A new method is presented to determine (1) the rate constant for the main reaction, (2) the rate constant for deactivation, (3) the effective diffusivity, and (4) the active enzyme distribution within a porous solid support by utilizing data of bulk substrate concentration versus time in a continuous stirred basket reactor. The method relies on an assumption of parallel deactivation mechanism with strong pore diffusional resistance with respect to substrate species. The data of hydrogen peroxide-immobilized catalase published in the literature are used to demonstrate the theory. A parameter determination procedure is also presented.