The invention relates to a device for producing a diesel fuel-water microemulsion and injecting said emulsion into a diesel engine. The aim of the invention is to create a device which allows a diesel fuel-water emulsion for the diesel engine to be made available in the motor vehicle. Said aim is achieved by the fact that diesel fuel from the diesel fuel tank (11) and water from the water tank (15) are premixed in a static mixing system (28MI) so as to obtain a raw emulsion and are directed to a device comprising three high-pressure cylinders (1, 2, 3).; The inlets of the first high-pressure cylinder (1) and the second high-pressure cylinder (2) are connected to the water/diesel fuel raw emulsion mixing system (28MI), the outlets of the first high-pressure cylinder (1) and the second high-pressure cylinder (2) are connected to the homogenizing valve (13), the inlet of the third high-pressure cylinder (3) is connected to the outlet of the homogenizing valve (13), and the outlets of the third high-pressure cylinder (3) are connected to the diesel engine (24). The three pistons of the three high-pressure cylinders (1, 2, 3) are part of a pressure booster whose driving piston (4K) is guided within a driving cylinder (4) which is connected to a hydraulic drive unit (7).