The capacity of simulation program ASPEN PLUSTM was tested on an example of wet catalytic oxidation of diluted aqueous phenol solutions. Phenol was chosen as a representative of bactericidal and difficultly decomposing pollutants of industrial waste waters. The aim consisted in the formulation of a three-phase reaction system including a laboratory autoclave and substances undergoing complicated successive reactions. The program employed the database of non-ideal liquid-vapour equilibria and dissolution of gaseous components and enabled simulation of a non-isobaric reactor with liquid and gaseous starting components and products. The created model of reaction system was treated by non-linear regression procedures in order to identify selected kinetic parameters of partial reactions, determine parametric sensitivities, optimize reaction conditions, and propose a continuous arrangement of wet oxidation with a tubular reactor.