Second-order nonlinear optical sol-gel materials containing a nonlinear optically active chromophore in the side chain were synthesized. The chromophore was covalently bonded to the silicon oxide network. Second-order nonlinear optical properties of the sol-gel films were investigated in terms of the second harmonic generation (SHG) and linear electro-optic (EO) coefficient measurement. The SHG coefficient, d(33) was found to be 20-44 pm/V at the fundamental wavelength of 1064 nm and the EO coefficient, r(33) was found to be 67-113 pm/V at 633 nm.