During the past few years attention has been drawn on chemical techniques that could be used to discolour textile wastewaters. We have studied the photocatalytic degradation of various dyes (Methyl orange, Azo carmine B, Coomassie Brilliant blue G250, Tartrazine, Calcon, Eriochrome blue SE, Solamine Red 4BL, Bismarck brown Y(G), Methylen blue, Black 5, Red 120, Morin) using TiO2 P25 Degussa as catalyst. All dye solutions underwent a decolourization. The kinetics of reaction have been studied and were found to be zero or first order with respect to the dye. It was compared with the adsorption properties. The effect of the addition of hydrogen peroxide has been studied. An enhancement of the rate has been observed in all cases and the order with respect to the dye's concentration in presence of the additive seemed not to change. It is difficult to give general view of the kinetics using these very different dyes but the process was found to be effective for the decolourization of textile wastewater.