This paper describes the use of bio-oil derived from the pyrolysis of waste wood in a single cylinder, air cooled, direct injection (DI), diesel engine developing power of 4.4 kW at 1500 rpm used in agricultural and standby applications. The combustion, performance and emission characteristics of the diesel engine fueled with three different emulsions made from wood pyrolysis oil (WPO) and Jatropha methyl ester (JME) are compared with those of JME and diesel operations. The WPO of 5%, 10% and 15% by volume is emulsified with 95%, 90% and 85% by volume of JME, denoted as X(1)JOE5, X(1)JOE10 and X(1)JOE15 respectively. The combustion of JME, X(1)JOE5, X(1)JOE10 and X(1)JOE15 starts earlier by 2.6 degrees CA, 2.3 degrees CA, 2.8 degrees CA and 2 degrees CA respectively compared to that of diesel at load. Shorter ignition delay and higher peak cylinder pressure are observed with JME and its emulsions with WPO. There is a significant reduction in the nitric oxide (NO) emissions by 2.5% when fueled with X(1)JOE15. The smoke opacity decreases by 25%, 26.7%, 22.1% and 18.2% for JME and its emulsions with WPO respectively, in comparison with diesel at full load. (C) 2013 Elsevier Ltd. All rights reserved.