We present a combined experimental and computational study on the recently reported oxysulfide Sr6Cd2Sb6S10O7. Our spectroscopy and photoelectrochemical measurements and tests for photocatalytic activity indicate the potential of Sr6Cd2Sb6S10O7 for photocatalytic applications. In particular, the transient photocurrent response shows a reproducible photogenerated current which depends on light intensity and which indicates an efficient electron-hole separation upon visible light illumination. Density functional theory calculations, combined with crystal orbital Hamiltonian population analysis, give insights into the electronic structure of Sr6Cd2Sb6S10O7 and the origin of its physical properties. Our comprehensive investigation into Sr6Cd2Sb6S10O7 reveals the roles of its polar structure, polar Sb3+ coordination environments, and the 5s2 lone pair in making this compound a potential candidate for solar water splitting photocatalysis.