Photocatalytic degradation of dye C.I. Acid Orange 7 in aqueous solution using TiO2/hydrogel nanocomposite under solar light simulating source was studied. Hydrogel based on chitosan, itaconic and methacrylic acid was modified with colloidal TiO2 nanoparticles synthetized by acidic hydrolysis of TiCl4 and commercial Degussa P25 TiO2 nanoparticles. SEM/EDX analysis confirmed the presence of TiO2 nanoparticles onto/into hydrogel. It was found that both types of photocatalysts efficiently removed the dye from solution, but sorption rates and photodegradation efficiency were higher in the case of colloidal TiO2 nanoparticles. They ensured complete discoloration of dye solution. The efficiency of the reused TiO2/hydrogel nanocomposite showed that photodegradation activity was maintained at satisfactory level after three repeated cycles of illumination. POLYM. COMPOS., 35:806–815, 2014. © 2013 Society of Plastics Engineers