Abstract: The present invention provides a novel process for synthesizing vanadium oxide V.sub.6 O.sub.13 with a filament-like morphology by thermally decomposing ammonium metavanadate NH.sub.4 VO.sub.3 in the presence of a compound which sublimes upon heating. The reaction is carried out in an inert gas flow. The V.sub.6 O.sub.13 synthesized according to this invention can be used as cathode active material in electrochemical batteries.