[NiL(3)]X(2) (where L = 2-aminoethanol and X is Cl-, Br-,I-, NO3-, 0.550(4)(2-) or 0.5SeO(4)(2-)) and [NiL(2)X(2)] (X is Cl-, Br-, or SCN-) have been synthesised from solution and their thermal study has been carried out in the solid phase. [NiL(3)]I-2 and [NiL(3)]SeO4 undergo reversible endothermic phase transitions upon heating (63-93 degrees C and 94-113 degrees C, respectively, for heating and 94-65 degrees C and 110-190 degrees C, respectively, for cooling), whereas [NiL(3)](NO3)(2) exhibits two successive reversible endothermic phase transitions (10-38 degrees C and 50-62 degrees C for heating and 56-48 degrees C and 19-(-8)degrees C for cooling). On the other hand, [NiL(3)]SO4 undergoes irreversible endothermic phase transition (99-112 degrees C) in the solid state. All these transformations are assumed to be associated with the conformational changes of 2-aminoethanol chelate rings. [NiL(2)(NCS)(2)] melts at similar to 168 degrees C and remains supercooled for a few days at ambient temperature. The initial temperatures of decomposition (T-i) of these complexes have been compared with those of the corresponding ethane-1, 2-diamine complexes of nickel (II).