A FTIR "home-made" cell is used to study the evolution of surface species and gas phase coupled with a mass-spectrometer (MS) for time-resolved analysis in static and dynamic conditions in order to gain further information about the variables that influence the mechanism of reduction of NO, stored. A preliminary IR study with simultaneous gas and surface spectra of Pt-Ba-Al2O3 and free-Pt catalysts implies that the platinum is necessary for the regeneration in the appropriate temperature range (200-400 degrees C). The use of different reducing gases (H-2, C3H6 or C3H8) shows that the distribution of reduction products and the temperature reaction window are correlated with the reducing molecule. Secondly, an operando MS-FTIR technique permits us to compare-a Pt-Ba-Al2O3 and Pt-K-Al2O3 catalysts under flow conditions during a complete NSR cycle, showing that barium containing catalyst allows better NSR performance. (c) 2007 Elsevier B.V. All rights reserved.