The effect of the nitrocarburizing process in pastes with heating in a chamber furnace on the structure and strength characteristics of 09Cr15Ni8Al corrosion-resistant steel was investigated. The technology of thermochemical treatment was developed, which included nitrocarburizing in pastes with heating in a chamber furnace at different holding times. The thickness of the diffusion layer and its microhardness were determined after nitrocarburizing. To determine the efficiency and select the modes of thermochemical treatment, tests were carried out for the investigated steel's strength characteristics. The main feature of the structure of the diffusion layers of valve steels, obtained by nitrocarburizing in the nitrogencarbon paste, is the presence of an inhomogeneous layer with clearly distinguished zones.