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.