A general model of a foam-bed reactor involving simultaneous gas absorption, reaction, and desorption has been developed. The model considers all coupled processes in the reactor. The reactive gas absorption and desorption in the foam section have been simulated via analysis of a single foam film surrounded by limited gas pockets. The model includes a sub-model to find out concentration profiles inside the surface element. A modular approach has been used to simulate a single foam film to obtain transient concentration profiles of the gas-phase reactant A and product P. Effects of various kinetic, physicochemical, operating, and system parameters like reaction velocity, diffusion coefficient, solubility, contact time, and holdup on fractional absorption and desorption of gas are studied.