AbstractOperando shell‐isolated nanoparticle‐enhanced Raman spectroscopy (SHINERS) with on‐line mass spectrometry (MS) has been used to investigate the surface species, such as NO, NOH, NO2, N2O, and reaction products of the NO reduction reaction with CO and H2 over supported Rh‐based catalysts in the form of catalyst extrudates. By correlating surface intermediates and reaction products, new insights in the reaction mechanism could be obtained. Upon applying different reaction conditions (i. e., H2 or CO), the selectivity of the catalytic reaction could be tuned towards the formation of N2. Furthermore, in the absence of Rh, no reaction products were detected. The importance of the operando SHINERS as a surface‐sensitive characterization technique in the field of heterogeneous catalysis provides routes towards a better understanding of catalytic performance.