Carbon monoxide (CO) is a versatile signaling molecule that is produced endogenously and is suggested to exert anti-inflammatory, anti-apoptotic, and anti-proliferative effects. Carbon monoxide releasing molecules (CORMs), such as [fac-Mn(CO)₃(Br)(bpCO₂)]^2-, (A, bpCO₂^2- = 2,2’-bipyridine-4,4’-dicarboxylate dianion), have potential to deliver therapeutic levels of CO to tumors to serve as an anti-cancer strategy. Because hypoxic tumors have significantly higher hydrogen peroxide (H₂O₂) concentrations compared to normal tissues, there are implications for physiological CO delivery by using endogenous H₂O₂ to trigger CO release from CORMs, such as A. However, the dynamics of H₂O₂ reactions with CORMs are not well understood. To assess the viability of using this class of reactions with CORMs in cancer therapy, we have undertaken a quantitative kinetics study of the H₂O₂ oxidation of the water-soluble complex, A. Previous studies in our group demonstrated that about 2.5 equivalents of CO were released upon H₂O₂ oxidation of A via pH-dependent kinetics that are first-order in both [A] and in [H₂O₂]. At higher pH’s, there is a greater presence of the more nucleophilic and reactive conjugate base of H₂O₂, the hydroperoxy anion, HOO^-. The present experimental studies employ stopped flow kinetics to evaluate this reaction’s mechanisms and key intermediates under more basic pH’s to investigate the role of HOO^-. Understanding these pathways is critical in using CORMs to apply the therapeutic potential of CO in several disease states featuring physiological H₂O₂.