A simple measuring technique for the linear electro-optic coefficients in electro-optic waveguides is described. The method is based on the direct evaluation of synchronous angle measurements obtained by prism coupling. No waveguide or electrode patterning is required. A model has been developed in order to simulate the relation between change in synchronous angle and applied electric field across the electro-optic waveguide. The measured values of the electro-optic coefficients in poled polymer waveguides are reported.