TiO2 nanorod array thin films were synthesized on fluorine doped tin oxide (FTO) glass substrate by the hydrothermal method. The prepared TiO2 nanorod arrays were characterized by X-ray diffraction, scanning electron microscopy and UV-Vis diffuse reflectance spectroscopy. The effect of different synthesis conditions was investigated on the growth and photocatalytic activity of the samples. X-ray diffraction results show that the main phase of TiO2 is rutile and nanorod growth significantly depends on the synthesis conditions. TiO2 nanorod array thin films were used for the photocatalytic degradation of methylene blue in aqueous solution under UV irradiation (254 and 365 nm). The hydrothermal synthesis conditions of TiO2/FTO sample were determined for maximum photodegradation efficiency. Total degradation of 94 % was achieved under 254 nm and 69 % degradation was achieved under 365 nm with TiO2/FTO sample prepared with initial HCl:H2O = 1:1 ratio, 1.0 ml TiCl4 at 180 A degrees C for 2 h hydrothermal growth. The apparent reaction rate constant was calculated to be 0.0108 min(-1) under 254 nm and 0.0044 min(-1) under 365 nm.