Two inorganic acids decorating titanium-oxo clusters (PTCs), Ti₆O₄(OⁱPr)₁₀(O₃P-Phen)₂(NO₃)₂ (PTC-251) and Ti₆O₄(OⁱPr)₁₀(O₃P-Phen)₂(HSO₄)₂ (PTC-252) (H₂O₃P-Phen = phenylphosphinic acid) have been synthesized under solvothermal conditions. As a result of the labile coordination sites of the {Ti₆P₂} unit, nitrite and sulfate adopt different capping mode. Besides, they also present different space packing. The photocatalytic H₂ evolution activities of these obtained PTCs have been studied, with sulfate decorating PTC-252 presenting a maximum H₂ production rate up to 110.95 μmol·g^-1·h^-1.