The full modeling and simulation of a multiannular photocatalytic reactor requires a thorough physical analysis of all the concurrent phenomena determinant of its performance: momentum and mass transfer in the homogeneous, nonuniform, fluid phases; radiation transfer in the fluid phases and across the flow physical boundaries; and heterogeneous photocatalytic reaction kinetics. In a previous work, an expression of the intrinsic kinetics for the degradation of perchloroethylene (PCE) based on a plausible reaction mechanism was proposed and experimentally validated. In this work, this expression is used in the physical modeling and mathematical simulation of a multiannular, bench-scale reactor. The reactor shows good effectiveness for the PCE degradation in polluted moist air. A radiation field model was developed to predict the local superficial rate of photon absorption (LSRPA) at each point on the reactor catalytic walls, which is needed to evaluate the local reaction rate. A 2-D mass balance was developed taking into account the intrinsic kinetics, as well as mass-transfer rate processes and the LSRPA calculated with the radiation field model equations. Predicted conversions show good agreement with experimental results with a root mean square error < 5.6%. (c) 2006 American Institute of Chemical Engineers.