The phase diagram of binary system of nematogenic compounds 4-n-pentyl phenyl 4-n'-hexyloxy benzoate (ME6O.5) and 4-cyanophenyl 4-heptyl benzoate (CPHB) shows the presence of induced smectic phase. In the present paper, we report the results of DSC, refractive index, and density measurements of different binary mixtures of (ME6O.5 + CPHB) throughout the entire composition range. The density and refractive index values have been analyzed to obtain orientational order parameters. We have fitted the experimental order parameters with the theoretical values from McMillan's theory for mixtures having smectic phase, and Maier-Saupe theory for others having nematic phase only.