Photo catalysis has become a very important area in the processes of wastewater treatment for the degradation of organic compounds. The most used photocatalytic are TiO2 and ZnO due to their low toxicity, chemically inert in the degradation processes, easy to obtain and relatively inexpensive. Although they have been widely used, methodologies for obtaining these materials to increase their photocatalytic activity are still being developed. Due to their nature, TiO2 and ZnO have a band gap of 3.2 approximately, which makes them activate only with energy that corresponds to the wavelength of ultraviolet light. The synthesis of ZnO it does by the hydrothermal method using different zinc precursors (acetate, nitrate and sulfate). The results show the obtaining of hexagonal crystalline phase in all cases with a variation in morphology. Its photocatalytic activity is evaluated in the degradation of methylene blue. ZnO obtained from zinc acetate shows greater photocatalytic activity by eliminating 66% of methylene blue. In this work the importance of the choice of the precursor in the synthesis of ZnO for specific applications is shown. In the case of the hydrothermal method, when using zinc acetate in the synthesis of ZnO, the material obtained has a greater photocatalytic activity for the degradation of methylene blue (25% more) compared to that obtained from zinc nitrate and zinc sulfate.