Biodiesel can be obtained from various resources. However, the usage of vegetable oils as biodiesel source may impact global food market. Therefore, scientists focus on searching new biodiesel sources which are non-edible and easy to obtain. Microalgae have gained much attention recently due to their high growing rates and high oil contents. The objective of this study is to identify availability of microalgae biodiesel in diesel engines as alternative fuel. Microalgae biodiesel was blended with diesel fuel with the volumetric ratio of 5%, 10%, 20% and 50%. Fuel properties of blends and pure microalgae biodiesel were found out and the performance characteristics and exhaust emissions of the engine fueled with blends were analyzed. The results showed that, although microalgae biodiesel caused a slight reduction in torque and brake power values, the emission values of the engine using microalgae biodiesel were improved. (C) 2013 Elsevier Ltd. All rights reserved.