The influence of the material of the alloying electrode (Armco iron, steel 45, chromium, tungsten, molybdenum, nickel, steels 38KhN3MFA and 30Kh13, hard alloys VK8 and T15K6), power parameters of the equipment for electroerosive alloying (discharge power), environment (air, argon, nitrogen), and duration of treatment on qualitative parameters of formed surface layer on steel 45 (structures, microhardness distribution, continuity and uniformity of the coating) is investigated. As determined, during electroerosive alloying (EEA) with chromium, molybdenum, nickel and other elements, the operating modes, which providing discharge power $N_{\textrm{p}}$ = 119.3–144.3 W at continuous alloying with productivity of 1.0–2.0 min/cm$^2$, are preferred. Investigations of the structure and properties of coatings obtained in air and argon showed that there is no significant effect of a neutral environment compared to an oxidizing one. Application of argon is not improve the quality of the layer. Application of nitrogen as an environment for EEA with nickel positively influences on properties of the layer. The structural features of the surface layers are determined, the main of them are as follow: subfine-grained structure, martensite phase, significant amount of residual austenite. As shown, after continuous EEA with chromium, thickness and microhardness of the white layer increase with increasing of EEA duration. The reserves of increasing the working properties of the hardened layer by methods of surface deformation are proposed.