Effect of the temperature of water as the ablation environment on the characteristics of TiO2 nanoparticles produced by laser ablation process in water has been investigated experimentally. The fundamental wavelength of a Q-switched Nd:YAG laser was employed to irradiate a high purity Ti plate in distilled water at different temperatures of 0, 20, 35, 50 and 65 °C. Produced nanoparticles were diagnose by UV–Vis–NIR spectroscopy, X-ray diffraction method, TEM, and SEM micrographs. Results show that with increasing the water temperature from 20 °C, size of nanoparticles was increased and their bandgap energy was decreased. Minimum ablation rate occured at the highest temperature. Crystalinity of produced nanoparticles also increased with increasing the temperature of water .