A kinetic study concerning water decolorization using a combination of low wavelength UV radiation (253.7 nm) and hydrogen peroxide has been performed. Kinetic studies were carried out in a specially designed flat plate reactor, made in such a way that almost "isoactinic" conditions are achieved. Results were analyzed in terms of a very simple kinetics expression. Absorbed radiation effects were duly quantified by means of a one-dimensional radiation field model. With experimental degradation rates, a kinetics expression relating the initial color (expressed in terms of initial total organic carbon) with the most important process variables was proposed and the decolorization kinetics parameters were obtained. The initial decolorization rates at 25 degrees C can be properly represented with an equation of the following form: R-TOC(0) = -kC(TOC)(0)e(a)(z).