Cation exchange was employed to intercalate the lattice of CdPS3 with both ruthenium tris(bipyridyl) cation, a good photoreducing agent, and methylviologen cation, an electron acceptor. The host lattice is diamagnetic and transparent in the visible and near-ultraviolet region of the spectrum, allowing excitation and spectroscopic observation of photoinduced electron transfer processes involving the host lattice and the intercalated species. The photoinduced charge transfer between these species was examined using photoluminescence and electron paramagnetic resonance spectroscopy. Cation vacancy centers in the CdPS3 host lattice are shown to be chemically and photochemically active.