Orientational order parameter is one of the important parameter of the liquid crystalline mesogens. This parameter governs nearly all physical properties of mesogens. Many methods are known for the estimation of orientational order parameter in liquid crystalline phase. In the present investigation the birefringence and dilatometric techniques have been exploited on some liquid crystalline CBOnO.m compounds with spacer n = 7, 10, 8, 5, and terminal group m = 10. Using density and birefringence data, the molecular polarizability and the orientational order parameter by Vuks and Neugebauer methods were evaluated and discussed the results with available data on number of liquid crystalline compounds.