A two-dimensional model describing the behavior of a batch cylindrical photoreactor has been validated through a series of photocatalytic reactivity runs. The light intensity radiation field produced by 1-6 external UV fluorescent lamps was modeled together with Langmuir-Hinshelwood kinetics and 4-nitrophenol (NP) and Degussa P25 TiO2 were used as the probe molecule and the catalyst, respectively. The experiments were carried out under different conditions of light intensity, photocatalyst amount and substrate concentration. The model parameters were the kinetic constant of substrate adsorption, desorption and degradation and the exponent of the power law expressing the kinetics dependence on the light intensity. A least-squares best fitting procedure was used to fit the experimental data to the model and find the four required parameters. A satisfactory agreement was obtained between experimental and calculated values of the observed pseudo-first order kinetic constant, with a coefficient of determination R-2 = 0.83. Notably, the present model is of general interest for cylindrical slurry photoreactors, where different molecules can be oxidized in the presence of several photocatalysts and it can be used, for instance, to accurately compare the performance of a set of catalysts. (C) 2014 Elsevier B.V. All rights reserved.