The metal ion complexes [Co(II), Ni(II), Cu(II) and Cd(II)] of some azopyrazolopyrimidine derivatives have been prepared and characterized using elemental analyses, molar conductivity, electronic and IR spectra. The azopyrazolopyrimidines are characterized by a high tendency towards complex formation with the neutral molecules coordinating to the metal ion as bidentate ligands. It is concluded that the ligands are bonded to the metal ion through the - or β-nitrogen atom of the arylazo group and the carbonyl oxygen of the pyrazolone ring where six- or five-membered chelate rings are formed. The apparent formation constants of the complexes in solution have been determined.