Carbon monoxide-releasing organic molecules are described herein. The molecules can be synthesized prior to administration (e.g., ex vivo) or formed in vivo. In those embodiments where the molecules are formed in vivo, reactants are administered under physiological conditions and undergo a cycloaddition reaction to form a product which releases carbon monoxide. In applying such reactions for therapeutic applications in vivo, the cycloaddition and CO release typically occur only under near-physiological or physiological conditions. For example, in some embodiments, the cycloaddition reaction and/or release of carbon monoxide occur at a temperature of about 37° C. and pH of about 7.4. Pharmaceutical compositions and methods for release carbon monoxide are also described.