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The combined steam and CO 2 reforming reaction of CH 4 was investigated using LaSrNiO x mixed oxides supported on Al 2 O 3 -modified β-SiC to elucidate the largely enhanced CO 2 conversion at an optimal concentration of Al 2 O 3 modifier. The dispersion of Al 2 O 3 on the SiC support simultaneously altered the dispersion of LaSrNiO x crystallites increasing their strength when combined with the Al 2 O 3 -modified SiC. Although all tested catalysts showed similar activation energies, the increased Al 2 O 3 dispersion on SiC at around 10 wt % Al 2 O 3 modifier was well-correlated with the increased dispersion of active perovskite-like La 2 NiO 4 crystallites which resulted in an enhanced catalytic activity. The formation of smaller NiO and La 2 NiO 4 crystallites through an intimate contact with Al 2 O 3 particles seems to be responsible for the suppressed aggregation of nickel crystallites during higher temperature reforming reactions. The higher amounts of CO 2 adsorption on the well-dispersed basic lanthanum and strontium oxides contained in the LaSrNiO x mixed oxides are also responsible for the enhanced CO 2 conversion. Observed surface properties including the crystallite size of active components, the reducibility of NiO, and the CO 2 adsorption property are explained in terms of the results obtained from X-ray diffraction, X-ray photoelectron spectroscopy, temperatureprogrammed reduction, CO 2 temperature-programmed desorption (CO 2 -TPD), and NH 3 -TPD analyses.