The aim of this project is to substantially improve the power out and efficiency of the open cycle gas turbine (GT) power plant in Miri. There are many different cooling the inlet air. The air can be cooled by either mechanical chillers or media type of evaporative. The method of Fog-Cooling System (media type of evaporative) is the most widely used cooling method and is used in this project for optimizing the power output by pre-cooling the inlet air of the gas turbine engine.