In the present work the degradation of nitrogen oxides (NOx) by concrete paving stones containing TiO2 to be applied in road construction is studied. A kinetic model is proposed to describe the photocatalytic reaction of NOx (combining the degradation of NO and the appearance and disappearance of NO2) in a standard laminar flow photoreactor irradiated with UV lamps employing only NO as the contaminant source. In addition, the influences of several parameters that can affect the performance of these stones are investigated, such as NO inlet concentration, reactor height and flow rate. The kinetic parameters present in the NO and NO2 reaction rate are estimated employing experimental data obtained in the photoreactor. The obtained model predictions employing the determined kinetic constants are in good agreement with the experimental results of NO and NO2 concentration at the reactor outlet. (C) 2010 Elsevier B.V. All rights reserved.