In the present paper, results of an experimental and numerical study of gas flows in radial micro-nozzles are reported. The radial micro-nozzle consists of two disks spaced apart by a less than one millimeter distance. To the inlet of the radial nozzle, a gas under high pressure is supplied; through the nozzle, the pressurized gas is ejected into ambient space. In the present study, we analyzed the flows in which the gas at the inlet to the micro-nozzle had a supersonic velocity. It was shown that, on the condition that the micro-nozzle width was smaller than some critical value, then, due to the wall friction force, a pseudo-shock arose in the micro-nozzle. In the pseudo-shock, the gas underwent deceleration to a subsonic velocity. A satisfactory agreement between the calculated and experimental data was achieved.