In this letter we report on preliminary results of heteroepitaxial growth of Ga0.51In0.49P on Si with a GaAs interlayer by low-pressure organometallic chemical vapor deposition (OMCVD). The surface morphologies and crystalline quality of the films were found to be critically dependent on the growth parameters of the initial GaAs buffer layer. Under optimum conditions, specular single-crystal Ga0.51In0.49P epilayers can be reproducibly obtained. Capacitance-voltage measurements show that the carrier distribution in the grown layer is very uniform. The 77 K photoluminescence spectrum exhibits a strong near-band-edge emission with a half-width of 22 meV. These results can compete with those reported previously for the OMCVD-grown GaxIn1-xP on GaAs substrates.