Developing a highly active and stable Ni-based catalyst is still a challenge for the generation of on-site hydrogen through steam reforming of long-chained hydrocarbons, such as kerosene fuels. Ni nanoparticles (ca. 5 nm) on mesoporous alumina prepared by atomic layer deposition (ALD) were employed in steam reforming of n-dodecane, and exhibited a turnover frequency (TOF) of 477.6 h(-1), whereas Ni nanoparticles on commercial alumina support prepared by impregnation method exhibited a TOF of 100 h(-1). The high activity of ALD Ni catalysts was ascribed to high reduction degree, as confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM), and H-2-chemisorption. A deactivation was also observed on the ALD prepared catalysts, which was ascribed to the weak metal support interaction, as confirmed by H-2 temperature-programmed reduction (TPR). The ALD Ni/Al2O3 catalysts were further modified with CeO2 and they showed enhanced stability with 8% deactivation degree in steam reforming of n-dodecane. Further characterizations of spent catalysts showed that the presence of CeO2 was favorable for stabilizing Ni nanoparticles by enhancing moderate metal-support interaction, and reducing the formation of coke on the interfaces of Ni CeO2. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.