In2S3–In2O3 films were used as photoelectrodes and photocatalysts for hydrogen production. The films were grown using a hydrothermal method for different reaction times (4, 6, 8, 12, 18 and 24h). The difference in the reaction time influences the presence of other crystalline phases, such as β-In2S3, In2O3, Ti3S4, and Ti5S8, on the film structure; the presence of these elements was verified by the XPS results. Furthermore, the mixture of phases generates different morphologies such as flowers, pyramids, and sheets. The best photoelectrochemical results were obtained from the films deposited at a reaction time of 6, 8, and 12 h, as these films have an OCP value of ∼0.3586, 0.3791 and 0.4771 VRHE and a photocurrent density of 3, 1.92, and 1.5 μA•cm−2 at 1.23 V vs. RHE, respectively. According to these results, the 12h/In2S3–In2O3 film has the highest donor density and the lowest Debye length, which enhances the efficiency of photogenerated electrons and electron-hole separation. Moreover, the highest photocatalytic hydrogen production was achieved with the 12h/In2S3–In2O3 film, which, in addition to presenting the most optimal photoelectrochemical properties, also has defects such as oxygen deficiencies, Ini and VIn, which could act as traps for electrons in the recombination process, increasing the reduction reactions at low energy and enhancing hydrogen production.