The linear electro-optic coefficients (Pockels coefficients) of two novel organic chromophores, doped in thin films of poly(methyl methacrylate) (PMMA), are determined through a simple experimental method based on a waveguide sample geometry. A DC electric field is applied onto each polymeric film inducing birefringence. This varies the polarization state of a laser beam passing through the film. Measuring these variations, the electro-optic coefficients can be determined for different values of the applied electric field. The microscopic molecular parameters, dipole moment mu and first order hyperpolarizability beta are calculated. The results indicate that the existence of ionic bonds at the edge of the molecule of a chromophore increases its dipole moment, while the presence of strong acceptors enhances its first order hyperpolarizability. (C) 2004 Elsevier B.V. All rights reserved.