A method of derivation of linear driving force approximation for diffusion and reaction processes in porous catalysts based on Laplace-Carson transform has been presented, The approximate model for any type of kinetic expression has been derived. Accuracy of developed model is good, especially in the range of small and intermediate Thiele modulus values that is used most often in cases of practice. This approximation yields a substantial simplification of analysis and computations and does not require any iterative and trial-and-error calculations.