Eleven iron-oxygen compounds prepared using standard laboratory syntheses were tested as precursors for carbon-carbon bond scission catalysts with the coal model compound naphthylbibenzylmethane in the presence of elemental sulfur and a hydrogen-donating solvent. The structure of the iron-oxygen catalyst precursor was found to be the most significant factor determining the reactivity of the catalyst produced. The reactivity of the iron-oxygen compounds showed little : apparent correlation with surface area, iron content, or water content. The iron-containing single-phase materials with the best catalytic activity at 400 degrees C were determined to be ferric oxyhydroxysulfate (Fe8O8(OH)(8)SO4), six-line ferrihydrite, goethite ((alpha-FeOOH), and akaganeite (beta-FeOOH). The worst iron-oxygen compounds were found to be wustite (FeO), two-line ferrihydrite, magnetite (Fe3O4), and maghemite (gamma-Fe2O3). The general order of reactivity of the iron-oxygen compounds toward carbon-carbon bond scission was found to be proto-oxyhydroxides > oxyhydroxides > oxides. All of the iron-oxygen compounds tested were at least as active as metallic iron (alpha-Fe). All of the active I catalyst precursors produced similar distributions of organic reaction products from the model compound. The best catalyst precursor tested was ferric oxyhydroxysulfate, which formed a catalyst which selectively cleaved carbon-carbon bonds at the a-naphthyl-methylene ("a") and the beta-naphthylmethylene ("b") positions with a model compound consumption of greater than 90% under the test; conditions. The ferric oxyhydroxysulfate was found to contain a relatively large amount of water and small amount of iron, 18% and 43%, respectively, by weight.