NOVELTY - Producing transition metal oxide film (I), comprises: (a) preparing a solution comprising at least one, preferably at least two precursors containing at least one of the elements A, M, Z and O, chelating agent and polar organic solvent having a boiling point below 150 degrees C at atmospheric pressure; (b) maintaining the solution with stirring to form a sol; and (c) implementing the sol as transition metal oxide film by depositing at least one layer of the sol to a substrate and calcining the deposited layer at 250-725 degrees C to produce the transition metal oxide film.    USE - The method is useful for producing transition metal oxide film, which is useful as an electrode material, preferably a positive electrode material, or as a protective material of the electrode material (all claimed) for a battery, preferably microbattery, or fuel cell.    ADVANTAGE - The method provides the transition metal oxide film which is thin, homogeneous, has low surface roughness, does not form cracks, exhibits good adhesion to the substrate, good electrochemical properties, good wettability and higher insertion capacity of greater than or equal to 60%, preferably greater than or equal to 90% of the theoretical reversible insertion capacity, preferably greater than or equal to 70%, preferably greater than or equal to 80%, in particular greater than or equal to 90%, and a specific capacity of greater than 70% after 20 (preferably 100) cycles of discharge, per unit mass.    DETAILED DESCRIPTION - Producing transition metal oxide film of formula (I), comprises: (a) preparing a solution comprising at least one, preferably at least two precursors containing at least one of the elements A, M, Z and O, a chelating agent and a polar organic solvent having a boiling point below 150 degrees C at atmospheric pressure; maintaining the solution with stirring to form a sol; and (c) implementing the sol as transition metal oxide film by depositing at least one layer of the sol to a substrate and calcining the deposited layer at 250-725 degrees C to produce the transition metal oxide film. The chelating agent is aliphatic di- or tricarboxylic acids comprising 2-20 carbon atoms and/or their salts.    A = alkali metal, preferably Li, Na and/or K;    M = metal or mixture of metals comprising transition metals, lanthanides or actinides, preferably Co, Ni, Mn, Fe, Cu, Ti, Cr, V and/or Zn;    Z1 = chemical element or a mixture of chemical elements of columns 13-15 of the Periodic Table, preferably B, N, P, Al, Si, Ge, In, Sn or Ga;    c = greater than or equal to 0, preferably 0; and    a, b, d = greater than 0, where a, b, c and d are selected so as to ensure electroneutrality.    INDEPENDENT CLAIMS are also included for:    (1) a sol comprising at least one precursors containing at least one of the elements A, M, Z and O, the chelating agent and the polar organic solvent.