The article presents the test results of an engine operating with diesel fuel (B5), turbine type JP-8 fuel and its 5 vol%, 10 vol%, 20 vol%, and 30 vol% blends with rapeseed oil methyl ester (RME). Additional fuel blend B10 was prepared by pouring 10 vol% of RME to diesel fuel to extend interpretation of the test results. The purpose of this study was to examine the effects of using jet-biodiesel fuel blends J5, J10, J20, J30, and B10 on the start of injection, ignition delay, combustion history, heat release, engine performance, and exhaust emissions. The engine performance parameters were examined at light 15% (1400 rpm) and 10% (2200 rpm), medium 50%, and high 100% loads and the two speeds: 1400 rpm at which maximum torque occurs and a rated speed of 2200 rpm. The autoignition delay and maximum heat release rate decreased, maximum cylinder pressure, and pressure gradients increased, whereas brake specific fuel consumption changed little and brake thermal efficiency was 1.0-3.6% higher when running with fuel blends J5 to J30 at rated speed compared with the data measured with neat jet fuel. The NOx emissions increased slightly, but the CO, THC emissions, and smoke opacity boosted up significantly when using jet fuel blend J10 with a smooth reduction of unburned hydrocarbons for jet-biodiesel fuel blends with higher CN ratings. Operation at a full (100%) load with fuel blend J10 produced more CO and exhaust smoke, whereas the combustion of identical fuel blend B10 showed the reverse trends reducing both pollutants at both engine speeds. (C) 2015 Elsevier Ltd. All rights reserved.