The excessive use of fossil fuels has led to significant environmental challenges, including global warming driven by carbon dioxide emissions and widespread air pollution. Essentially, focusing on sustainable and clean energy sources is necessary for the future of humanity and our planet. Through evolution, nature has solved this energy problem through the natural photosynthesis process. Manganese plays a crucial role in natural photosynthesis, specifically within the oxygen-evolving complex of photosystem II and therefore manganese has garnered significant interest for its potential use in catalytic, photocatalytic, and photoelectrochemical water oxidation, as well as in various other applications, due to its crucial role in natural photosynthesis. Therefore, This review focuses on the photocatalytic and photoelectrocatalytic properties of different manganese compounds and discusses various characterization techniques, with a special focus on electrochemical and photoelectrochemical methods used for assessing photoactive semiconductors. The primary goal of this text is to offer a comprehensive summary of the advancements in this area. Additionally, it sheds light on various approaches and strategies used in this field that could be applicable in related areas of interest. The review concludes with an outlook and final thoughts on the subject.