A giant linear electro-optics (Pockels) effect (up to17 pm V-1) (for wavelength about 435 nm) in ZnOcrystalline films doped with fluorine and deposited on bareglass has been found. For description of the observedphenomenon, a complex approach including self-consistent band structure calculations together with an appropriate moleculardynamics simulation of the interface structure was applied.Experimental ellipsometric and refractive index measurementsconfirm an efficiency of the mentioned approach for descriptionof the observed interface (between the film and glass)processes. The origin of the observed effect is caused by substantial non-centrosymmetric charge density distributionbetween the ZnO wurtzite-like crystalline films and the bareglass substrate, as well as by additional charge densitypolarization caused by fluorine atoms.