The chromatographic properties on thin layers of poly(ethyleneimine) cellulose of sixteen compounds containing the pyridine and/or adenine ring have been studied. Chromatographic mobilities have been examined as a function of the concentration of lithium chloride or sodium formate buffer in the chromatographic solvent. These data provide a rationale for the development of rapid and simple separation methods that should prove useful in the study of pyridine and adenine nucleotide metabolism.