Ni/MgO catalyst for internal steam reforming in a molten carbonate fuel cell (MCFC) is severely deactivated by the vaporized alkali carbonates. Especially, lithium species affect the poisoning process and many researchers reported the possibility that the reaction of Li species with Ni and supports changes the material properties. High temperature treatment of commercial catalyst mixed with lithium carbonate powder resulted in lower activities, and the degree of deactivation depended on the amount of lithium species. For the improvement of poisoning resistance the support was substituted with MgO-TiO2 mixed oxides. It was exhibited from the activity test that geikielite (MgTiO3) was almost deactivated and qandilite(Mg2TiO4) had the poisoning resistance. Karooite(MgTi2O5) showed the intermediate property. The XRD analysis confirmed the phase transition induced by the inter-reaction of Li, Ni and supports. The TPR patterns showed that the stronger interaction of Ni with supports made the catalyst more resistant to the poisoning.