Nowadays, the development of fuel cell is getting more and more inseparable from the production of hydrogen. Long-chain hydrocarbons steam reforming is a feasible way for hydrogen supply. Herein, various nickel-ceria-praseodymium (Ni-Ce-Pr) catalysts have been prepared by a sol-gel method. Multiple parameters during catalyst preparation, including the amount of Ni, the content of doped Pr and the calcination temperature, were systematically studied for tuning the catalytic performance for n-dodecane steam reforming in a fixed-bed reactor under 15 mL/g(cat)center dot h at 600 degrees C and water-to-carbon molar ratio of 2 at 0.1 MPa. Reaction data showed that both the amount of Ni and the content of doped Pr will greatly affect the n-dodecane conversion and hydrogen production. Additionally, the calcination temperature during catalyst preparation showed a big influence on its performance for n-dodecane steam reforming. After optimization, 10Ni-CePr2-600 exhibits the highest activity and stability for n-dodecane steam reforming, accompanying with the lowest rate of coke deposition (0.015 g(c)/g(cat)center dot h). The structure and oxygen vacancy of the catalyst was characterized by H-2-TPR, Raman, and X-ray photoelectron spectroscopy (XPS). The superior activity and stability of 10Ni-CePr2-600 are ascribed to the strong interaction between NiO and support along with abundant oxygen vacancies in the Pr-doped ceria.