Three catalysts, vanadyl sulfate hydrate (VS), ceric (IV) sulfate (CS), and molybdenyl acetylacetonate (MA) were studied for their effectiveness in enhancing oxygen delignification. Bleaching experiments on a mill-produced hardwood kraft pulp under acidic conditions showed that, under acidic conditions, catalytic oxygen delignification is superior in reducing kappa number as compared to an alkaline oxygen delignification stage. Cyclic voltammetry was used to study the redox behaviour of the catalysts. The effectiveness of catalysts in delignifying pulp was correlated with their ability to oxidize lignin model compounds. The voltammogram of VS showed the oxidation of vanadium to be an irreversible one-electron transfer process. VS was found to be effective in catalyzing the oxidation of vanillyl alcohol (a phenolic lignin model compound). CS was found to be the most efficient of the three catalysts with a high reduction potential and reversible electrochemical behaviour. Gas Chromatography analysis of the reaction products between CS and veratryl alcohol (a non-phenolic lignin model compound), carried out in a mini-reactor, clearly illustrated the effectiveness of CS in catalyzing the oxidation of veratryl alcohol.