Pharmaceuticals and other organic micropollutants are increasingly found in water sources. The UV/H2O2 process is a suitable technology to degrade these pharmaceuticals. A kinetic model is presented to predict pharmaceutical degradation during UV/H2O2 treatment. Reactions with background constituents in the water matrix, such as (bi)carbonate, nitrate and NOM were considered as well as hydroxyl radical and carbonate radical reactions with the pharmaceuticals. The kinetic model is validated by collimated beam experiments. In several water matrices a good agreement between measured and modelled degradation was found, for direct photolysis as well as advanced oxidation. For only 5 of the 36 compounds, the model over or under predicted the measured results. Possible explanations are: pH effects during photolysis and radical scavenging by NOM. The influence of each reaction incorporated in the kinetic model was studied by a sensitivity analysis. The sensitivity study showed that nitrate reactions can also be relevant in UV (LP) applications when there is no hydrogen peroxide and low concentrations of NOM. (C) 2014 Elsevier B.V. All rights reserved.