The completion of the polycondensation of sol-gel derived organic-inorganic hybrid silica by heat treatment was studied for powder samples prepared from vinyltrimethoxysilane and vinyltriethoxysilane. The appropriate temperature for the completion of the prepared submicron powdery samples from both starting compounds was determined through thermogravimetric analysis. The completion or incompletion of the polycondensation was elucidated by means of several instrumental methods in addition to a light scattering test. The lowest heat treatment conditions for the particles from vinyltrimethoxysilane and vinyltriethoxysilane are 170 degrees C and 180 degrees C, respectively, for 24?h. The morphologies of the heat treated samples were found to be slightly different depending on the starting material used.