The cobalt(II) and nickel(II) chelates of Schiff bases, derived by condensing 4-butyryl-3-methyl-1-phenyl-2-pyrazolin-5-one (BMPP) with o-, m-, p-phenylenediamine, benzidine, and ethylenediamine have been synthesized and characterized by elemental analyses, thermogravimetric analyses (TGA), conductance data, magnetic measurements, IR, 1 H NMR, 13 C NMR, mass, and electronic spectroscopies. Each of the Schiff bases was an ONNO donor to metal forming chelates formulated as [M(L)(H 2 O) 2 ] n with M ¼ Ni(II) and Co(II) and L is the di-anion of the Schiff base. The monomeric (n ¼ 1) and dimeric (n ¼ 2) species of these metal chelates, based on available evidence, are suggested.