The main aim of this work is to optimize the operation parameters of using evaporative cooling system such as height of pads and air velocity. To achieve that study the effect of different pad height (1.0 and 2.0 m) and different air velocities (1.5, 3.0, 4.5 and 6.0 m s^-1) on air temperature, relative humidity, temperature reduction, cooling efficiency and cooling capacity. The obtained results indicated that the hourly temperature of air increased gradually until it reached the peak and then decreased during period from 9 AM to 6 PM. Also, the air temperature decreases with increasing pad height. The hourly relative humidity of air decreased gradually until it reached the peak and then increased during period from 9 AM to 6 PM. The temperature reduction increased from 3.3 to 8.8, 6.4 to 14.4, 5.5 to 16.5 and 5.3 to 18.4 °C when the pad height increased from 1.0 to 2.0 m, respectively for 1.5, 3.0, 4.5 and 6.0 m s^-1 air velocities. The highest value of temperature reduction was 18.4 °C was found with 2.0 m pad height and 6.0 m s^-1air velocity. The cooling efficiency increased from 34.3 to 61.7, 53.4 to 94.6, 49.6 to 94.4 and 54.1to 98.8 % when the pad height increased from 1.0 to 2.0 m, respectively for 1.5, 3.0, 4.5 and 6.0 m s^-1 air velocity. The highest value of cooling capacity was 629.1 kW was found with 2.0 m pad height and 6.0 m s^-1air velocity.