In this paper we present the study results of nanopowders properties produced by electrical explosion of wires in argon-oxygen and argon-air mixtures with different ratios of oxygen and air (0.5-30 vol. %). The products of aluminum, titanium and copper wires explosions were studied. The effect of the synthesis conditions on the metal content in the nanoparticles and their phase, chemical and size composition is discussed. The oxygen addition of 10-30 vol. % leads to a reduction in the metal content in the particles and to the formation of metals oxide. The small additives of reactive gases (< 2 vol. %) into the inert gas in the discharge chamber can be used for production of metal powder.