The structure and chemical composition of composite and multicomponent borided layers obtained by a new method that combines the chemical electroless and plasma boriding techniques are described. Quantitative X-ray microanalysis examinations show that on the surface of nickel-phosphorus coated steel borided at 923 K three boride phases of the type (NixFe1-x)(4)B-3, (NixFe1-x)(2)B and (FexNi1-x)B formed, whereas in the samples borided at 1123 K only two borides (Fe1-xNix)B and (Fe1-xNix)(2)B are present. The shape and the distribution of the phases depends on the thickness of the Ni-P layer deposited on the steel substrate before boriding. The thicknesses of boride zones obtained on nickel coated steels are much greater than those obtained on the same steel without nickel coating. Also the diffusion zone between the Ni-P layer and the steel increases during boriding, which improves the adhesion of the layer to the substrate. The composite layers obtained show a high wear resistance, with their resistance to corrosion being markedly greater than that of uncoated and only borided steel.