[en] Experiments on neutral gas injection in the TO-1 tokamak chamber are described. The control of gas valve has been carried out according to the set programm and automatically as well, depending on the amplitude changes of the MHD activity of discharge in the time duration. The gas injection makes it possihle to regulate the density value within the wide range of its change. Dependencies of relative velocity of MHD activity increase in time on the charge characteristics were obtained, and measurements of some plasma parameters were carried out during the injection process. The automatic valve control makes it possible to increase considerably plasma concentration and to keep it at a new level during the greater part of charge pulse duration in the tokamak