An experimental study is conducted to evaluate the performance and exhaust emissions characteristics of diesel fuel blends with 8%, 16% and 24% (by vol.) diethyl ether (DEE), in a standard, experimental, single-cylinder, four-stroke, high-speed direct injection (HSDI), 'Hydra' diesel engine located at the authors' laboratory. The tests are conducted using each of the fuel blends or neat diesel fuel, with the engine working at three different loads. Fuel consumption, exhaust smoke, and regulated gas emissions such as nitrogen oxides, carbon monoxide and unburned hydrocarbons are measured. The differences in the performance and exhaust emission parameters of the three DEE/diesel fuel blends from the baseline operation of the diesel engine, i.e., when working with neat diesel fuel, are compared. Combustion chamber and fuel injection pressure diagrams are obtained, and heat release rate analysis of the experimentally obtained cylinder pressure diagrams is performed, revealing some interesting features of the combustion mechanisms. These results and the widely differing physical and chemical properties of DEE against those for diesel fuel are used to aid the interpretation of the observed engine behavior. It is revealed that this fuel, which can be produced from biomass (bio-DEE), is a promising one for diesel engines. (C) 2012 Elsevier Ltd. All rights reserved.