The combustion engine is intended to be used in the drive of land vehicles, aerial vehicles and water vehicles, as well as in various kinds of machinery. The engine has the pair of two-chamber cylinders (2), in which double- ended pistons 3 are located and are directed toward themselves oppositely by the angle 180° and compressed together via the crankshafts (4). This shaft consists of two crank elements (4a) and (4b), which are linked together rotationally backward by means of the spacer bearing (5). The compress function of the crankshaft (4) is realized with the use of two connecting rod pairs 7a and 7b, from which each connecting rod is linked on the one side to with one crank element (4a) and (4b), whereas the second connecting rod ends are linked to one of shafts (8), out of which each shaft is connected with one of pistons (3) via valve rod (9). In the middle of each cylinder's wall (2) the outlet channel of compressed air is located (10) as well as the outlet channel of products of combustion together with air (11). In the head (12) of each cylinder (2) and in the compartment (13) the fuel injector (14), the water vapor injector (15) and the ignition element (16) are located. Water vapor injectors (15) are attached to the device for dosing water vapor (21), which is supplied by the water vapor generator (23). The HHO generator is used in order to supply the engine, and as a result obtained oxygen is led through the ionizer (30) to the gas connector (31), where the ionization of oxygen with hydrogen takes place, whereas the formed mixture of gases is transferred to the fuel system of the engine.