Catalytic activity and selectivity of Ni catalysts for solar CO2-reforming of methane were examined under direct irradiation of the catalyst by solar-simulated, concentrated Xe-arc lamp light, using a small-scaled transparent (quartz) packed-bed reactor. The Ni catalysts (17 wt %-Ni), supported with alpha-Al2O3, SiO2, ZrO2, and TiO2, were tested, and the Ni/alpha-Al2O3 showed the best activity and selectivity under the solar simulation, as well as under direct irradiation by infrared light. With the Ni/alpha-Al2O3 catalyst at the energy flux density of the incident light = 810 kW m(-2) and at the GHSV = 18700 h(-1), more than 90% of methane was chemically converted to syngas, in which 16% of the incident light energy wag stored as chemical enthalpy. The activity data were compared to those for the catalyst irradiated by infrared light or UV-cut Xe light at various reaction temperatures or incident energy flux densities. This comparison indicated that the solar-simulated reforming with the Ni/alpha-Al2O3 was scarcely enhanced by UV-photochemical effect and that the activity was mainly determined by the thermochemical effect or the catalyst-bed temperature.