An accurate prediction of natural gas water content is an important parameter in proper designing of natural gas production, transmission, and processing facilities. The aim of this study is to describe an accurate method for predicting water content of sweet and sour natural gases, where the obtained results by the proposed method show good agreements with the experimental data. The proposed method provides good estimates of the equilibrium water vapor content of sour natural gas for a range of conditions, including H2S contents of 0-50 mole % with CO2 contents of 0-40 mole %, pressures from atmospheric to 100,000 KPa for sweet gas and 70,000 KPa for sour gas, and temperatures from 10C-150C for sour gases and 10-200C for sweet gases.