Antotherrnal reforining (ATR) has been performed Over 2 wt % Ni/Ce-Zr-O/monolith catalysts in a fixed-bed reactbr at atmospheric pressure with complete conversion of n-dodecane at 700 degrees C. The O/C ratio (0.6-1.1) was investigated. At optimal O/C ratio (0.9) the maximum H-2-rich syngas yield could be achieved with both upstream (746 degrees C) and downstream (709 degrees C) monolith, teniperatures above 700 degrees C. BET surface area and Ni dispersion were measured, while temperature-programmed oxidation (TPO), ternperature-programmed reduction (TPR), scanning electronic microscopy (SEM), and X-ray diffraction ())were used to characterize carbon deposition and nickel status. TPO and SEM showed that carbon deposited on the monolith decreases With increasing O/C ratio and along the axial direction from upstream to doWnstream. The effect of catalYst calcination treatment (700 to 1200 degrees C) on the yields of H-2, CO/CO2, and C-1-C-4, hydrocarbon products was also studied with ATR O/C ratios at 06 and 0.9. The amount of deposited carbon decreased with increasing calcination temperature and a carbon-ree operation could be achieved on the 1000 degrees C-calcined catalyst. The high-temperature calcination resulted in the decrease of H-2 yield but increased- the yield of C-1-C-4 hydrocarbons. Quantitative H-2 chemisorption and in situ TPR-TPO indicated the toss of metallic Ni due to the formation of Ni2SiO4 from the solid-state-interaction of Ni and cordierite, which was confirmed by XRD of the catalysts calcined at 1200 degrees C.