Despite the present great lead of ion engines in development level, performance and life for sizes up to several kW, new interest in magnetoplasmadynamic thrusters for higher power levels (up to hundreds of kW) has arisen in recent years. Mission studies showed specific impulse values between 1000 and 2000 s for orbit raising and orbit transfers for optimized mass savings and trip times, and advantages for MPD propulsion even with relatively low efficiencies. With the probable realization of the SP-100 nuclear space power plant, sufficient power would also be available for steady state MPD propulsion, so that the benefits of these thrusters versus pulsed ones could be utilized; i.e., the ruggedness and simplicity of power and propellant conditioning and the about 3 orders of magnitude smaller cathode erosion. But there are also disadvantages of steady state thrusters; e.g., with quasi-steady ones (but with other geometries) the achieved efficiencies and specific impulses were in some higher. The research work covered in this report deals with these and related problems: in chapter two, the experimental results with nozzle-type and cylindrical thrusters are presented. The influence of cathode position, ambient pressure, anode gas injection and propellant type on the performance is investigated. The thruster design studies and the heat transfer calculations for the MPD thruster with a radiation-cooled anode are reported.