L-cysteine modification of palladium (Pd) electrodes have been characterized using various electrochemical and surface analytical techniques such as cyclic voltammetry (CV) reductive/oxidative desorption electrochemical Impedance spectroscopy (EIS) X-ray photoelectron spectroscopy (XPS) and specular reflectance Fourier transform infrared (FT-IR) spectroscopy The electron transfer reaction of L-cysteine modified Pd electrode was probed by employing Fe(CN)(6)(3-/4-) redox couple using cyclic voltammetry and electrochemical impedance The CVs results revealed a quasi-reversible voltammograms for the Pd modified electrode demonstrating that the electron transfer is not blocked due to surface modification EIS results for the Pd modified electrode showed a decrease in the resistance in comparison with the bare Pd electrode The surface coverage was 6 4 +/- 0 4 x 10(-10) mol/cm(2) The XPS survey study for the L-cysteine modified Pd electrode exhibited the presence of sulfur on the surface High energy resolution XPS and FTIR indicated that the L cysteine molecules are sulfur bonded to the Pd surface These results suggest the modification of palladium surface by the L cysteine amino acids (C) 2010 Elsevier B V All rights reserved