Application of protective coatings based on light elements having strong interatomic bonds is one of the most practical and promising methods of decreasing the rate of erosion (wear) of the first wall of thermonuclear reactors due to ion sputtering and blistering. We carried out experiments for determining the surface radiation resistance and hydrogen permeability of a steel having a protective nitrided layer. In order to develop the protective layer on the 08Kh18N10T steel, it was subjected to nitriding in a stream of high purity nitrogen at 1000/sup 0/C. The specimens having a nitride layer were bombarded simultaneously with helium and hydrogen ions; besides this, hydrogen permeability of the specimens having a zone of internal nitriding was studied.