Surface immobilized peptides and proteins containing the tripeptide sequence Arg-Gly-Asp (RGD) are of interest because of their ability to bind to members of the integrin superfamily of cell-surface receptors and thereby direct cellular haptotaxis. Two-component counterpropagating gradients of organothiols terminated with an RGD-containing tetradecapeptide and the cell-adhesion-resistant thiol, mercaptoundecanol (MUD), were electrochemically generated by coupling in-plane electrochemical potential gradients with the electrosorption reactions of organothiols to vary the composition laterally. One- and two-component gradients formed from model alkanethiols and peptide-terminated thiols as a function of local composition were probed by spatially resolved electrochemical stripping analysis and Fourier transform infrared external reflection spectroscopy (FTIR-ERS), using the IR spectra to map the local composition and the shift in desorption peak potential, E-des(0), to assess the degree of surface heterogeneity. The measured lateral composition profiles, Gamma(x), are well-described by a linear potential gradient model. However, because the two-component gradients are formed in a two-step process, in which a full monolayer of the first component is desorbed in a spatially dependent manner, there is a lower density of adsorbate molecules remaining in the transition region due to partial desorption of organothiols leading to less organized molecular packing.