Abstarct: In this research, we have been used hydrothermal-assisted sol-gel processing for the preparation of nano-sized BaZrO3 and CaZrO3 ceramics using alkoxide precursors. The influence of several synthesis parameters such as temperature, solvent and precursor have been investigated on the morphology, crystalline size and purity of the produced powders. Fourier transform infrared spectroscopy, X-ray diffraction, TG/DTA analysis and scanning electron microscopy have been used for this purpose. The results showed that the single phase BaZrO3 with 10 nm particle size, has been prepared by hydrothermal hydrolysis of barium ethoxyethoxid and zirconium ethoxyethoxide precursors in ethoxyethanol at 100 ˚C. In addition, XRD and IR showed that highly crystalline single phase CaZrO3 has been prepared by hydrothermal hydrolysis of calsium ethoxyethoxid and zirconium ethoxyethoxide precursors in the 1:1 mixture of ethoxyethanol and toluene at 50 ˚C. The band gap of the produced barium zirconate powders have been determined by the method proposed by Wood and Tauc in the rang of 4.78 and 5.08 eV. The B1 samle (single phase barium zirconate with the smallest particle size according to the scherrer equation) has been tested in the photocatalytic degredation of methylene blue. The UV-Vis spectroscopic results showed that the maximum adsorption (19.5%) of this pigment was obtained after 75 minutes in the 5 ppm solution in dark. The irradiation of this solution under the UV-light has been degraded up to 40% of the methylene blue pigment after 60 min.