We describe the charge transfer interactions between photoexcited CdS nanorods and mononuclear water oxidation catalysts derived from the [Ru(bpy)(tpy)-Cl](+) parent structure. Upon excitation, hole transfer from CdS oxidizes the catalyst (Ru2+ -> Ru3+) on a 100 ps to 1 ns timescale. This is followed by 10-100 ns electron transfer (ET) that reduces the Ru3+ center. The relatively slow ET dynamics may provide opportunities for the accumulation of multiple holes at the catalyst, which is necessary for water oxidation.