© 2018 Bulgarian Academy of Sciences.Due to the energy shortage, environmental pollutions and climate change, the issues of energy conversion technologies have become more and more significant. In recent years, organic Rankine cycle has become a leading technology for the conversion of heat into useful work or electricity. This promising technology uses an organic fluid which has high molecular mass hydrocarbon compound, low critical temperature, and pressure as a working fluid. In this paper, energy and exergy analysis of a waste air's heat-driven organic Rankine cycle, which has two turbines, two pumps, an evaporator, a condenser, a recuperator, and a feed fluid heater, is performed using R114, R600, R600a and R245fa organic fluids. The organic Rankine cycle's performance parameters are evaluated depending on various evaporation temperatures and the inlet pressure of the high-pressure turbine. The results indicate that R245fa has the highest thermal efficiency also the highest net power is obtained for the R600 working fluid. Also, the thermal efficiency and the net power increase with the increment of the evaporation temperature and these features raise before and then decreases with the increasing high-pressure turbine inlet pressure in the analysis of ORC.