Early investigations on the use of tyre pyrolysis oil (TPO) blended with diesel of 10-90% exhibited longer ignition delay, as a result of the lower cetane number of TPO, as well as the blends. In the experimental investigation, TPO was blended with Jatropha Methyl Ester (JME), whose cetane number is higher than that of diesel, and used as an alternative fuel in a single cylinder, four stroke, air cooled, direct injection (DI) diesel engine developing 4.4 kW. Five different blends of varying TPO, from 10% to 50% at steps of 10% on a volume basis, were considered for the investigation. Interestingly, the combustion and emission behaviour of the engine deviated after 20% TPO in the blend. There was a reduction in the efficiency with 30%, 40% and 50% TPO in the blend at full load. The combustion, performance and emission behaviour of the engine fueled with JMETPO blends, are compared with those of diesel and JME operation and presented in this paper. (C) 2013 Elsevier Ltd. All rights reserved.