With multichannel detection, in situ Surface-Enhanced Raman spectroscopy (SERS) is demonstrated to provide a viable and valuable means of examining adsorption and reactions at transition metal surfaces in gas phase environments. especially at high pressures and elevated temperatures of relevance to heterogeneous catalysis where other vibrational techniques are of limited utility. In fact, an enticing vhtue of SERS is the ability to acquire time-nzsolved spectra; with the advent of charge-coupled device (CCD) technology, real-time sequences even in the subsecond time regime zue now becoming straightforward. In this work, adsorption and reactions at rhodium-high pressure gas interfaces are investigated at tempera-s up to 350 'C, systems including nitric oxide, carbon monoxide and oxygen on rhodium catalyst surfaces axe studied in a flow reactor. For example, the temporal replacement of adsorbed CO by NO, as well as temperature-induced changes in surface composition, are followed on a seconds timescale by means of a spectrograph-CCD detector arrangement. Such results illustrate the neat-time capabilities of the pnzsent SERS in heterogeneous catalytic systems.