© 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.In the present study, biodiesel was produced from waste cooking oil and canola oil mixture as a ratio of 50% (v/v) by applying the transesterification method. The fuel properties of diesel and biodiesel fuels were measured considering standard methods. Afterwards, the impacts of different injection pressures on energy and exergy efficiencies of a single-cylinder, four-stroke, naturally-aspirated, water-cooled, direct-injection diesel engine fuelled with diesel and biodiesel fuels were performed under a constant engine speed of 1400 rpm. The performance parameters of energy and exergy analyses for each fuel were calculated and compared with each other. It may be concluded that biodiesel shows similar trends with diesel in terms of energy and exergy analyses. The maximum energy and exergy efficiencies of the engine operated with diesel were found to be at 24.509% and 21.275% respectively under the original injection pressure (190 bar); meanwhile the maximum energy and exergy efficiencies of the engine fuelled with biodiesel were determined to be at 22.129% and 20.052% respectively under an injection pressure of 210 bar. The energy and exergy efficiencies of biodiesel have increased with increasing injection pressure. Furthermore, exergy destruction values of the engine were found to be between 61.623% and 64.437% for diesel, and between 58.905% and 62.794% for biodiesel.