Abstract. A major enterprise for scientists worldwide is the search for alternative fuels and molecular hydrogen (H₂) is a promising candidate. Its large-scale technical production needs to involve water-oxidation catalysts from inexpensive and abundant materials. Here, a water-oxidizing Co-based catalyst film (CoCF) is investigated. We review and extend our previous X-ray absorption spectroscopy (XAS) measurements (at Helmholtz-Zentrum Berlin/BESSY) by comparison to LiCoO₂, a Co^III compound of similar structure and composition. Further evidence is presented that the bulk oxidation state of cobalt in the CoCF is 3+. We propose that the catalyst film is composed of interconnected complete and/or incomplete Co-oxo cubanes possibly forming a disordered network of the basic Co_3/4(μ-O)₄ units.