For operation of industrial air compressors, conventional wisdom dictates that breathing outside air, which has lower temperature, will reduce the air compressor power consumption. In addition, many energy professionals and reliable sources (Parekh, 2000; Kaya et al., 2002; U.S Department of Energy, 2004; Hick, 2006) advocate the use of cooler air to reduce compressor power consumption. However, experimental results are not available to support the conventional wisdom. The purpose of this thesis is to experimentally investigate the effect of inlet air temperature on an oil-flooded rotary screw compressor located in the University of Alabama. This experiment is set up in a controlled environment. More specifically, a data acquisition system with digitally controlled fluids is developed to control the air demand imposed on the compressor. A range of inlet air temperatures are investigated based on local weather conditions. The injected oil temperature can be modified slightly by restricting the air flow through the air cooler. A design of experiments technique is utilized to evaluate the influence of inlet air temperature, inlet oil temperature, and air flow rate on the compressor power. The results show that inlet air temperature has little or no contribution to the compressor power. Moreover, the collected data shows that power consumption does not vary with inlet oil temperature. The results also show that as the inlet air temperature increases, the isentropic efficiency increases.