Binary and ternary complexes of the type M-Y and M-X-Y [M = Co(II), Ni(II), Cu(II) and Zn(II); X = 4-bromo-2-{(E)-[(2,3-dimethylphenyl)imino]methyl}phenol and Y = 1-{(E)-[(2-chloro-4-fluorophenyl)imino]methyl}naphthalen-2-ol] have been examined pH-metrically at 27 ± 0.5 °C and at constant ionic strength, μ = 0.1 M (KCl) in 75 : 25 (v/v) 1,4-dioxne-water medium. The stability constants for binary (M-Y) and ternary (M-X-Y) systems were calculated.