The almost complete conversion of a powder mixture of the elements into the perovskite-type MgxCyNi3 compound has been obtained in two steps, applying the SHS technique followed by an isothermal treatment at 1123 K. No evidence was found for Mg loss due to volatilisation, as well as of unreacted C, at the end of the preparation. Two new ternary phases, that may be referred to as Mg2+xNiCy and Mg1+xNi2Cy, grew during the combustion process; though different, their crystal structures appear to be strongly related to those Of Mg2Ni and MgNi2, respectively. Isothermal treatments at 973 K failed in the formation of the perovskite-type compound as a single product, since it was found coexisting with Ni and Mg1+xNi2Cy, probably on account of the relatively short reaction times. The samples were characterised by means of XRPD and SEM-EDS analyses after each step of preparation. (C) 2003 Elsevier Ltd. All rights reserved.