The formation of binary and ternary complexes of zinc(II) with bromide, iodide, and thiocyanate ions and 2,2′-bipyridine (bipy) has been studied by calorimetry in dimethylformamide (dmf) at 25 °C. The formation of the ternary complexes [ZnXm(bipy)n](2 –m)+(denoted as [1mn]), such as [111], [112], and [121] for X = Br and I and [111], [112], [121], and [122] for X = SCN is revealed, along with the binary complexes [ZnXn](2–n)+(n= 1–3 for X = Br, n= 2 or 3 for X = I, and n= 1, 3, or 4 for X = SCN) and [Zn(bipy)n]2+(n= 1–3), and their formation constants, reaction enthalpies, and entropies were obtained. The thermodynamic parameters are discussed together with those for the (2,2′-bipyridine)chlorozinc(II) complexes previously determined. A four-co-ordinate structure is suggested for [ZnX2(dmf)2](X = Br or I), [ZnX3(dmf)]–(X = Br, I, or SCN), and [Zn(NCS)4]2–, and thus the six-co-ordinate, octahedral structure of [Zn(dmf)6]2+ changes upon complexation. The complexes [Zn(NCS)(dmf)5]+ and [Zn(bipy)n]2+(n= 1–3) remain octahedral. The extent of formation of the [111] complex is weak in all halide systems. The [121 ] complex is dominant in the chloride system, significant in the bromide, but very weak in the iodide system, and the reaction enthalpies and entropies suggest that an octahedral–tetrahedral equilibrium, [ZnX2(bipy)(dmf)2](Oh⇌[ZnX2(bipy)](Td)+ 2dmf (X = Cl or Br), is established in solution. On the other hand, the [112] complex, which is not found in the chloride system, becomes dominant in the bromide and especially so in the iodide system. The formation of the [ZnI (bipy)2]+ complex, [Zn(bipy)2]2++ I–→[Znl(bipy)2]+, is accompanied by unusual ΔH⊖ and ΔS⊖ values, implying that a specific interaction operates between iodide ion and 2,2′-bipyridine molecules in the vicinity of the zinc(II) ion.