An oxidation method using dilute nitric acid solutions under solvothermal conditions has been developed to synthesise a series of polypyridine-polycarboxylic acids. It has been successfully applied to a range of methyl substituted polypyridines including symmetrical and asymmetrical 2, 2′-bipyridines; 2, 2′: 6′, 2 ″-terpyridines and; 2, 2′: 6′, 2 ″: 6 ″, 2‴-tetra-pyridines and yields crystalline polypyridine-polycarboxylic acids in a single step. ...