Waste heat recovery plays an important role in energy resource management. Low grade waste heat could be recovered by Organic Rankine Cycle (ORC). This is the same as the Rankine cycle and an organic fluid is used as working fluid. In this work the effects of using two-component mixtures with different temperature glides during phase change, on performance of Organic Rankine Cycle are studied. Four two-component mixtures are selected: n-pentane/n-butane, isopentane/isobutene, n-pentane/isobutene and isopentane/n-butane. In this study for more reasonable comparison of thermal recovery the inlet and outlet temperatures of heat source heat carrier fluid and its mass flow rate are considered to be constant. Results show that in the use of two-component mixtures in comparison with pure fluids, approximately 9% increase in energetic and exergetic efficiencies for simple configuration and 14% in configuration with the internal heat exchanger can be achieved with respect to the temperature glide match in the condenser and evaporator.