The hydrolytic co-condensation of hydrophobic phenyltriethoxysilane(PTES)and hydrophilicγ-aminopropyltriethoxysilane(APS)was investigated in toluene and water by using hy-drochloric acid(HCl)catalyst.A soluble and meltable poly(aminopropyl/phenylsilsesquioxane)(PAPSQ)was formed by controlling HCl amounts,APS/PTES molar ratios,water/silane molar ratios (Rw/si),organic co-solvents and re-equilibration steps as well.The compositions of PAPSQ bearing aminopropyl and phenyl groups with the capping of trimethylsilyl group were confirmed by element analysis,fourier-transform infrared spectroscopy(FT-IR),nuclear magnetic resonance(NMR)and thermogravimetric analysis(TGA).Differential scanning calorimetry(DSC)was employed to char-acterize the melting behavior of the product.PAPSQ can be easily employed as functional molecular building blocks for the synthesis of diverse and novel inorganic-organic materials.