CH4/CO2 reforming over La2NiO4 and 10%NiO/CeO2-La2O3 catalysts under the condition of supersonic jet expansion was studied via direct monitoring of the reactants and products using the sensitive technique of cavity ring-down spectroscopy. Vibration-rotational absorption lines of CH4, H2O, CO2 and CO molecules were recorded in the near infrared spectral region. Our results indicated that La2NiO4 is superior to 10%NiO/CeO2-La2O3 in performance. In addition, we observed enhanced reverse-water-gas- shift reaction at augmented reaction temperature. The formation of reaction intermediates was also investigated by means of time-of-flight mass spectrometry and there was the detection of CHx+, OH+ and H+ species. (C) 2007 Elsevier B.V. All rights reserved.