Complexes of Co-III with pyrazine-2,6- and pyridine-2,6-dicarboxylic acids have been synthesized. The ligands act as tridentate coordinating through the heterocyclic ring nitrogen and two carboxyl oxygens in both the complexes. Single crystal X-ray analyses of both the complexes reveal the structures as distorted octahedral, Co sitting at the center and surrounded by one tridentate ligand and three ammonia. The counter anion is nitrate.