2,3-Bis(hydroxyimino)-1,2,3,4-tetrahydro-pyrido[2,3-b]pyrazine (H2L), prepared from 2,3-diaminopyridine and cyanogen-di-N-oxide, has been converted into nickel(II), palladium(II), copper(II), cobalt(II), and cobalt(III) complexes (H2L) with a 1:2 metal:ligand ratio. The ligands coordinate through the two N atoms, as do most vicinal dioximes. [(LH)Cl(H2O)Cd], contains a six-membered chelate ring. [Co(HL)2(L')Cl] has also been prepared using triphenylphosphine, triphenylarsine, thiophene and chloride as axial ligands. The structure of the vic-dioxime and its complexes are proposed on the basis of elemental analysis, i.r., H-1-n.m.r. and uv-visible measurements.