A method is described for preparing a niobium suboxide represented by the formula, NbOx, in which 0.7<x<1.3. The method involves reacting NbOy (in which y<1.8<2.1) with a stoichiometric amount of niobium metal, in the presence of hydrogen. The niobium suboxide produced by such method may be used to fabricate anodes for solid electrolyte capacitors.