The removal of colour from textile dyeing waste water by using Ni (0.5, 1.0, 1.5 and 2.0% weight) doped semiconductor titanium dioxide was studied. Photocatalytic degradation studies were carried out for malachite green using Ni doped TiO2 in aqueous solution and the progress of the reaction was observed spectrophotometrically at 616 nm. The effect of various operating parameters like pH, concentration of dye, dose of semiconductor and light intensity has been studied to optimise reaction conditions. A tentative mechanism has been proposed for the photocatalytic degradation of malachite green, involving hydroxyl radical as an active oxidizing species. It was observed that the pseudo-first order model was more favorable for the degradation of malachite green using Ni doped TiO2. This was observed that the degradation is more effective and fast for 1.0% Ni-TiO2. This photocatalytic degradation may prove to be an ecofriendly and cost effective process for the removal of hazardous and toxic dyes present in effluents of textile, printing and dyeing industries.