Photoelectrochemical water splitting to generate hydrogen uses the renewable sources to meet the daily increasing energy demand. Lots of metal oxides have been investigated as photoanode in a photoelectrochemical cell, where hydrogen generation occurs on the metal counter electrode. Despite great efforts, the solar-to-hydrogen conversion efficiency is still not fully up to expectations. On the other side, p-type semiconductors can be employed to generate photoelectrons that directly reduce water on the photocathode to hydrogen. Copper based metal oxides, including binary and ternary oxides, represent a promising class of p-type semiconductors due to their low cost and abundance in the earth. From the perspective of photoelectrochemical energy applications, they typically have large photocurrent, higher conduction band level for large hydrogen evolution driving force, and very positive onset potentials as well. However, the fatal issues that copper-based metal oxides suffer are the stability and efficiency in the aqueous electrolyte solution. In our presentation, we will show our recent efforts in both experiment and theory to manipulate copper-based metal oxides from the perspectives of morphology, geometry and electronic band structure by passivating the surface, engineering electronic band structures, and optimizing hydrogen evolution co-catalysts with the aim to achieve the long-term photostability and improve the solar-to-hydrogen conversion efficiency. The resultant nanostructures could be used as photocathode in photoelectrochemical cell for solar hydrogen generation.