Abstract A study of the heat capacity and magnetic susceptibility of MgNi 2 was undertaken to evaluate the report by Voss that this compound is ferromagnetic at temperatures below 235°C. The results of the investigation reveal no evidence of ferromagnetism in this Laves phase. MgNi 2 is found to be a moderately strongly paramagnetic material with a susceptibility which is practically constant between 25 and 450°C. Thermomagnetic analysis shows a very slight but abrupt drop in the susceptibility at 194°C, and heat-capacity measurements reveal a very small thermal anomaly at the same temperature. The effects are thought to be associated with some type of irregularity in the lattice, such as the defect structure which occurs when a nickel atom replaces a magnesium atom in the MgNi 2 lattice. Third-Law entropies of MgNi 2 at temperatures up to 555°K are also presented.