Abstract: A method of obtaining mechanical energy utilizing H.sub.2 O-plasma that is generated in multiple steps. The general field of art of the invention is that of producing a reactive thrust by using plasma. The mechanical energy provided by the invention is produced by explosion of electrically conductive plasma which is generated by dissociating H.sub.2 O. At the first step H.sub.2 O (gas) produced by a gasifier is reduced to a plasmatic state by electrical discharge. At the second step the plasmatic gas is treated by a further and stronger electrical discharge and by high-frequency induction heating, and the energy level of the plasma is raised to a point at which a plasma jet is ready to be produced. At the third step, the plasma jet is generated by periodically modulating the high voltage for the second electrical discharge, and a high-pressure thermal explosion reaction is caused by synchronizing the generation with compression of the plasma jet.