The behavior of plasma flow, generated by a D.C. plasma spraying gun, is simulated in a time-dependent 3 D. design. The high-temperature and high-velocity plasma plume is generated by a simple model based on Joule effect. The criterion of validation is the thermal efficiency while the only adjustment parameter is the length of the plasma column inside the anode. The transient plasma flow issuing in air atmosphere is reproduced. The plasma behavior is quite similar to that observed by fast-image video. Moreover, the centerline plasma plume properties are in agreement with experiment measurements, especially close to the torch exit and downstream the laminar-to-turbulent transition.