<p>This research investigated the photocatalytic properties of alkaline-earth hydrides, XH₂ (X = Ca, Ba, Mg, and Sr) based on their band structure. Photocatalysis relies on two processes, light absorption and redox reactions, which are a function of several factors, and in particular the bandgap energy (Eg), valence band Edge Potential (EVB), and conduction band Edge Potential (ECB) positions. Using computational methods, this research presented an assessment of the band structure and photocatalytic properties of these hydrides in order to complement existing characterizations by identifying future opportunities and concerns. Given that the hydrides were distinct in their band structure we were able to conclude that they also were dissimilar in their ability to photocatalyze reactions. In particular BaH₂ combines, Eg and redox potential, suggesting applicability for a range of photocatalytic processes. SrH₂ was able to absorb visible light due to a narrow bandgap, however the conduction band position prevented it from reducing hydrogen. While CaH₂ and MgH₂ had a large bandgap, and thus only worked with Ultraviolet (UV) light, they both had strong redox potentials. Among the investigated compounds, CaH₂ demonstrates the most promising properties for future photocatalytic applications, owing to its optimal bandgap energy and well-aligned band edge positions that favor efficient charge separation and redox reactions. This assessment expands our knowledge of hydride photocatalysts and may create pathways for tuning them using techniques such as doping or coupling with other materials. This study will also aid in the development of methods and technology for hydrogen generation and water decontamination as we move towards more sustainable processes in either area.</p> Graphical Abstract <p>Graphical representation of photocatalytic activity of XH₂ (X = Ca, Ba, Mg, and Sr).</p>