The catalytic activity and stability of LaNiO3 and La2NiO4, prepared using a citric acid complex method, have been investigated for partial oxidation of methane (POM) to synthesis gas. The catalysts were characterized by thermo-gravimetric analysis (TG), temperature-programmed reduction (TPR) and temperature-programmed desorption of ammonia (NH3-TPD). The results show that the catalytic activity and stability of La2NiO4 are higher than those of LaNiO3, due to the stronger interactions between Ni and La2O3 in La2NiO4 and to its lower acidity as demonstrated by TPR and NH3-TPD. TG result indicates that carbon deposition occurs on both catalysts, and the carbon species deposited on La2NiO4 are mainly metal carbides, while on LaNiO3 are mainly graphite.