Coordination compounds of compositions [Ni(taa) (ttcH)] (1), [Ni(teta)(ttcH)] (2), [Ni(sper)(ttcH)]·5H2O (3), [Ni(chxn)2(ttcH)] (4) and [Ni(1,3-pn)(ttcH)(H2O)] (5), where taa = tris-(2-aminoethyl)-amine, ttcH3 = trithiocyanuric acid [1,3,5-triazine-2,4,6-trithione], teta = triethylenetetramine, sper = spermine [(N,N′-bis-(3-aminopropyl)-1,4-butanediamine], chxn = trans-1,2-diaminocyclohexane, 1,3-pn = 1,3-diaminopropane, (the ligands are depicted in Scheme 1) have been prepared and characterized by C, H, N, S analysis, i.r. and u.v.-vis. spectroscopies and magnetochemical measurements. Those complexes containing water were also studied by thermal analysis. X-ray analysis of [Ni-(taa)(ttcH)] revealed a trigonal bipyramidal geometry around the NiII centre, which can be increased to octahedral by a non-bonding interaction between Ni and the S atom of the trithiocyanuric dianion [Ni–S(3) = 2.6650(10) Å].