Cs2.5H0.5PW12O40-SiO2 composite combined with (3-aminopropyl)triethoxysilane exhibited greater activity and selectivity for hydration of alpha-pinene at 333 K in a triphasic system (alpha-pinene/water/solid acid) compared to previously reported water-tolerant catalysts such as zeolites, polymer-resins (Amberlyst 15 and Nation-H), oxides, and liquid acids such as H3PW12O40 and H2SO4. The selectivity toward alcohols, including mono- and dialcohols, was approximately 80% over Cs2.5H0.5PW12O40-SiO2 composite.