The temperature variation of orientational order parameter in binary mixtures of two nematic compounds viz P-(p-ethoxy-phenylazo) phenyl Valerate (EPPV) and N-(p-propoxybenzylidene)p-pentylaniline (PBPA) has been estimated using refractive index and density data. The higher order parameter has been estimated. Employing the Humphries-James-Luckhurst theory the entropy of the transition of the mixtures at different concentrations has been computed. It is observed that the increase in the value of entropy of the transition is associated with the increase in the pair potential of the molecules in the mixtures.