Pathways of dehalogenation catalyzed by reduced Co corrins in the presence of various Co reductants are not well understood. Dehalogenation of CCl4 was determined in reaction systems containing a corrin (vitamin B12, cobinamide dicyanide, or aquocobalamin), reductant [Ti(III), dithiothreitol, or S2-/cysteine], buffer (pH 8.2), and CCl4. Transformation products in both the headspace and soluble reaction mixture were determined using GC/MS, HPLC, NMR, or TLC/autoradiography. Products in the presence of titanium(III) citrate, which yields the Co(I) form of the corrin, were mostly hydrogenolytic and included predominantly CH3Cl and CH4. More highly halogenated products were formed in the presence of thiol reducing agents, which yield the Co(II) form of the corrin. These products included CH2Cl2, CO, and formate in the case of dithiothreitol. Sulfide/cysteine reductants were least effective in promoting reductive dehalogenation with the major products identified as CHCl3, CS2, 2-oxothiazolidine carboxylic acid...