The urgent need for sustainable energy solutions has intensified research into materials capable of efficiently harvesting solar energy for hydrogen production. In this study, we investigate the photocatalytic properties of two hydride double perovskites, Cs2CaCdH6 and Rb2CaCdH6, using density functional theory (DFT). Building upon previous structural, electronic, and optical characterizations, we focus on their light absorption behavior and band edge alignment with respect to water redox potentials. Both compounds crystallize in a cubic Fm3̅m structure and exhibit indirect band gaps of 2.13 eV (Cs2CaCdH6) and 2.30 eV (Rb2CaCdH6), placing them within the optimal range for visible-light photocatalysis. Their absorption spectra confirm strong optical response in the UV–visible region. Band edge calculations indicate that the conduction band minima lie slightly above the hydrogen evolution potential, while the valence band maxima are well below the oxygen evolution threshold. These energetic positions satisfy the thermodynamic requirements for overall water splitting. Despite the modest reduction overpotentials, the results support the potential of Cs2CaCdH6 and Rb2CaCdH6as viable photocatalysts for solar-driven hydrogen production. This work contributes to the identification of non-oxide hydride perovskites as emerging candidates in photocatalytic energy conversion.