A potentiometic study has been carried out to reveal the coordination properties of 1,2-bis(4-benzylpiperidine)glyoxime (BPG), via its reaction with certain transition metal ions, Ni(2+), Cu(2+), and Zn(2+), and to determine the stability constants of the complexes formed. The experimental conditions were arranged to achieve all of the measurements and coordination in aqueous solution (mixed ethyl alcohol (10 %) and water (90 %)) at (25 +/- 0.1) degrees C and an ionic background of 0.1 mol.dm(-3) NaCl. The overall stability constants log beta(n) values of all species formed in solution together with the dissociation constants of the ligand were calculated by use of the SUPERQUAD computer program. The dissociation constants of the ligand BPG are 2.830, 6.066, 6.966, and 9.510. The chemical species present in the solution under our experimental conditions were demonstrated by the use of speciation diagrams.