A method of making an oxochlorin comprises the steps of oxidizing a chlorin to produce a mixture of hydronchlorin and oxochlorin, and then oxidizing the hydroxychlorin in said mixture, preferably with DDQ, to produce a mixture consisting essentially of oxochlorin. The step of oxidizing a chlorin is carried out by exposing the chlorin to alumina, typically in the presence of an oxidizing agent such as air or alumina. The oxidizing steps may be carried out in an organic solvent such as toluene. The chlorin is preferably a C-methylated chlorin, and is preferably metalated.