Abstract: To date, the separable performance equations for deactivating catalytic reactions in the strong pore diffusion resistance regime have only been solved for first order reaction and first order independent deactivation. Here we extend that analysis to all combinations of reactant-controlling first and second order reaction with first and second order independent deactivation. We then show how to evaluate the pertinent rate constants from experiments in reactors with either plug flow of gas (packed bed reactors) or mixed flow of gas (recirculating, Carberry, or Berty type reactors). The results of studies show that in the diffusion influenced regime, the conversion decreases with time more slowly than in the diffusion free regime. Besides, the characteristics of concentration-independent deactivation and separable kinetic rate form have also been discussed.