Different compositions of TiO2-polyaniline composites were prepared via chemical oxidative polymerisation of aniline over TiO2 nanoparticles followed by hydrothermal treatment. The prepared composites were characterised by various physicochemical techniques. From UV-VIS digital replay system (DRS) analysis, the shifts of the absorption maximum towards the visible region are indicated and transmission electron microscopy analysis showed that the particle size of TiO2 is reduced after incorporation of polyaniline. The photocatalytic activity of visible light responsive polyaniline modified TiO2 in the degradation of 4-nitrophenol was studied. The percentage degradation was monitored using a UV-VIS spectrophotometer. About 92% degradation was obtained with polyaniline modified TiO2.