Nanocomposites of TiO2/chitosan (nTC) were synthesized by hydrothermal process at 200 degrees C. Photo-catalytic activity of the nanocomposites was studied with degradation of malachite green (MG) in aqueous medium. Structural and physico-chemical properties of the obtained nanocomposites were characterized by XRD, SEM, BET, FTIR, and particle size analyzer. Complete photodegradation of MG was successfully achieved with the aid of the nanocomposites. The optimum photocatalytic degradation conditions, irradiation time, irradiation power, and amount of catalyst were studied. Photocatalytic activity of the synthesized nanocomposites in terms of degradation of MG was compared with that of undoped TiO2 (synthesized by our team) and chitosan under normal conditions. It was concluded that the synthesized nanocomposites had better photocatalytic activity. The best result (100% degradation) was obtained with amount of nTC of 0.25 g and irradiation time of 120 min.