The original CCOR equation of state shows great deviation in estimating vapour densities. This is characteristic for all cubic equation of state where temperature dependent parameters are determined by vapour pressure and liquid phase densities reproduction, In the modified CCOR equation of state (MCCOR) the temperature dependent parameter gamma was separated to improve representation of vapour phase densities along saturation line. In this work the reliability of the MCCOR equation was investigated. Comparing these results with that obtained by the original CCOR equation shows that the MCCOR equation gives better values.