Nuclear magnetic resonance (NMR) is shown to provide insight on the electronic properties of the chemisorption bond to-metallic electrodes of high specific surface area. The C-13-NMR of CO on Pt and Pd reveals the metallic character of the bond. The effect of varying the electrode potential on various NMR parameters has been studied in situ at-room :temperature. On platinum, the change in the spectral line position with potential was about 50-70 ppm/volt. However, on palladium, no change in the spin-lattice relaxation time with the electrode potential could be detected so far, thus indicating a small change, if any, in the charge transfer between the CO and the surface with the electrode potential.