Mathematical modeling of the molar concentrations profile of ethanol, acetaldehyde and ethyl acetate inside the catalyst particle is presented. This kinetic mechanism is based on the system of non-linear reaction diffusion equations. Modified Adomian decomposition method is employed to derive the general analytical expressions of molar concentrations of ethanol, acetaldehyde and ethyl acetate for all possible values of the parameters Φ i, γ i and α i (i = 1, 2, 3). Analytical results are compared with the numerical results, a satisfactory agreement is noted. Valid and invalid region of the solution for all concentrations are provided. These analytical results are useful to understand the behavior of the system. © Pleiades Publishing, Ltd., 2016.