Under the conditions of thermal electric-arc plasma in a plasmachemical reactor (PCR) with "cold" (CW) and "warm" (WW) walls, catalysts were synthesized and/or regenerated to be used for conversion of methane with steam. The "plasma" samples thus produced were characterized by means of electron microscopy, X-ray diffraction, and chemical analyses. It was established that the plasma samples are reduced 2-4 times as fast as their conventional analog G56A. Upon application of an external high-frequency (HF) discharge, the reduction rate of the plasmachemically synthesized samples rose by about 10%. The catalysts synthesized in a CW PCR had lower activity than their industrial analog G56A, while those synthesized in a WW PCR had activity comparable to that used in the industry (HIMKO Company, Vratsa, Bulgaria); moreover, under certain technological conditions, they were more active (by up to 10%), e.g., in the case of heterogeneous catalytic interaction between methane and water steam with applied HF discharge. (C) 2004 Elsevier B.V. All rights reserved.