The present work is devoted to applying modified Tao-Mason (mTM) equation of state (EOS) to highly associated fluids including water (H 2 O), amonia (NH 3), methanol (CH 3 OH), and ethanol (C 2 H 5 OH). In order to sim-plify the TM EOS, some modifications were carried out. Further, in the present study, new version of the temperature-dependent parameters sec-ond virial coefficient (B 2) was applied to the mTM. New equations have been proposed for other parameters appeared in the EOS. The calculations of thermodynamic properties of above-mentioned fluids using mTM cover the ranges from dilute vapor or gas to saturated and compressed liquid phase as well as supercritical region. The thermodynamic properties in questions are density, enthalpy, entropy, heat capacity at constant pressure and constant volume, and also speed of sound. It is found that mTM EOS is capable of predicting thermodynamic properties of associated fluids in vapor and supercritical regions with acceptable accuracies.