Production in submerged culture of ferroverdin, the ferrous chelate of the p-vinylphenylester of 3-nitroso-4-hydroxy-benzoic acid, has now been obtained in a chemically defined medium. When ferric ions are replaced in this medium by cobaltous ions a brown-red, chloroform-extractable pigment is produced by the micro-organism. Elementary composition, i.r. and n.m.r. spectra of the purified compound, as well as structures of reduction derivatives, suggest that the pigment contains three molecules of the same ligand found in ferroverdin bound to trivalent cobalt.