Oxygen non-stoichiometry in oxides play an important role in the photovoltaic (PV) and photoelectrochemical (PEC) performances of TiO2/Sb2S3 and ZnO/Sb2S3 heterostructures. Sb2S3 nanostructure is grown on TiO2 and ZnO nanorods using chemical bath deposition (CBD) and a novel one-step thermolysis process. PV and PEC performances are better when TiO2 is devoid of oxygen vacancies, whereas for ZnO these are better in presence of oxygen vacancies. Heterostructures made by 3-MPA complex thermolysis process is found to be superior compared to the CBD process.