Zirconium carbide, titanium carbide, zirconium nitride and titanium nitride. which are promising candidates for the ceramic matrix of inert matrix fuel (IMF) to transmute long-lived actinides were sintered using the spark plasma sintering (SPS) technique. Dy2O3(20 wt%) was added as a surrogate for Am2O3 and the sintering behaviours of Dy2O3 dispersed carbide or nitride matrix composites were compared with that of the matrix. The spark plasma sintering conditions consisted of a rapid heating rate of 75 K min(-1) and a very short holding time of 1-4 min at maximum temperatures ranging from 1773 to 2000 K. Dy2O3 dispersed carbides and nitrides with about 80%, of theoretical density were obtained by spark plasma sintering with a rapid heating rate and a short dwelling time. When Dy2O3 was added to the matrix, the shrinkage of the carbide or of nitride composites was initiated from a lower temperature than its matrix material during the heating stage. In the case of TiC and TiN, microstructural observation exhibited that Ti is soluble in dysprosium oxide and densification is enhanced around the oxide phase. (c) 2006 Published by Elsevier B.V.