Biphasic intergrowth La2MnNiO6-MgO composite oxide containing 30 wt% La2MnNiO6 was synthesized by ammonia aqueous (25 vol.%) co-precipitation method calcined at 1100 degrees C and investigated in the catalytic combustion of methane. Compared with the corresponding pure double perovskite-type oxide La2MnNiO6, the composite oxide La2MnNiO6-MgO exhibited much higher catalytic performance (T-50=548 degrees C,T-90 = 628 degrees C) and exceptional thermal stability. The excellent performance of La2MnNiO6-MgO was explained by various characterizations, such as XRD, ICP, H-2-TPR, XPS, and TEM techniques. The catalytic activity of La2MnNiO6-MgO prepared by biphasic intergrowth method is superior to La2MnNiO6/MgO obtained by impregnation technique, mechanical mixing of La2MnNiO6 and MgO, and pure La2MnNiO6. The better performance of La2MnNiO6-MgO for methane catalytic combustion reaction is ascribed to a strong intergrowth interaction between La2MnNiO6 and MgO during the synthesis process. Therefore, the La2MnNiO6-MgO composite oxide can be deemed as an attractive candidate as a catalyst for the combustion of methane. (C) 2013 Elsevier B.V. All rights reserved.