NiO-Y2O3 stabilized ZrO2(YSZ)composite is the state-of-the-art material for the anode support of planar solid oxide fuel cells(SOFCs).To improve its fracture toughness(KIC),lanthanum orthoniobate LaNbO4 which presents a rubber-like behavior in the monoclinic form that contains domains in two crystallographic orientations separated by highly mobile boundaries at ambient temperature is added to the mixture of YSZ and NiO at a weight ratio of 47:53.LaNbO4 is synthesized by the method of solid state reaction and the content of LaNbO4 in the composite is in the range between 5 and 30 wt%.