[SiO2]x[TiO2]1-x(x = 0.1, 0.2, 0.3, 0.4) powders were prepared by hydrothermal reaction of titanium isopropoxide (TIP) and tetraethyl-orthosilicate (TEOS) stabilized in acidic ethanol/water solution. The size and phase of TiO2 particles were controlled by adjusting the SiO2 content and the composition of the solvent system. The microstructure and photocatalytic activity of the prepared SiO2-TiO2 nanoparticles were characterized by XRD, TEM, BET, Raman and UV visible spectroscopic techniques. The major phase for all the prepared samples was anatase. The particle size of 0.3SiO2-0.7TiO2 powders prepared with excess amount of ethanol (REtOH = EtOH/alkoxide molar ratio = 120) was about 8.7 nm, while that of the sample prepared with small amount of ethanol (REtOH = 4) was 9.9 nm. The photocatalytic activity of these composite powders under excess ethanol was 1.5 times higher than that of pure TiO2 with respect to the decomposition of 1,4-dichlorobenzene (DCB).