Performance of evaporative cooler with rectangular pads of materials like rigid cellulose, corrugated paper, high density polythene and aspen is theoretically analyzed. The variation of saturation efficiency and cooling capacity with air mass flow rate is shown. The saturation efficiency decreases and outlet temperature of air increases with mass flow rate of air for all the materials. The saturation efficiencies vary from 93.7 to 77.5 % for different materials with aspen material having highest efficiency and cellulose having the lowest. Higher thickness of the material increases wetted surface area and it gives higher efficiency. Cooling capacities increase with mass flow rate of air indicating large mass of air being cooled but with decreasing efficiency. Cooling capacities range from 13408 to 56686 kJ/h for different materials with aspen material having highest cooling capacity and cellulose having the lowest. The outlet temperature of the air ranges from 28.8 to 26.5 0C with different materials with aspen material giving the lowest outlet temperature and cellulose material giving the highest. Large size coolers with higher pad areas allow greater mass flow rates of air and their cooling capacities are higher. However , reduction in the outlet temperature of air depends on thickness of the pad and wetted surface area per unit volume of the material. Such coolers will require adequate flow rate of water for complete wetting of the pad surfaces.