The photocatalytic activity of TiO(2) films synthesized via the sol-gel process has been measured as a function of UV irradiation time and substrate temperature. Fourier-transform infrared spectroscopy has been used to address the chemical changes in stearic acid and block copolymer Pluronic F127 films deposited on the photocatalytic surface. When the temperature of the photocatalytic substrate was raised above 50 degrees C, the removal of stearic acid from the surface was strongly affected by a process involving evaporation, whereas Pluronic F127 revealed a superior stability. Our study shows that heat enhances the photocatalytic activity, suggesting the importance of an accurate temperature control in photocatalytic efficiency measurements.