Surface electrochemical potential gradients were prepared by poising the two ends of a thin An strip at different potentials relative to a common solution Ag/AgCl reference couple. The small resistivity of the Au film resulted in a linear gradient in surface electrochemical potential, enabling spatially resolved electrochemistry. With no applied potential, a self-assembled monolayer (SAM) of an organothiol was formed on the electrode surface. Upon potential application the SAM was stripped in regions with local potentials cathodic of the reductive desorption potential, while regions sufficiently anodic of that potential maintained full monolayer coverage. A transition region was produced between the bare areas and those retaining full monolayer coverage. Carboxylic acid modified, fluorescently doped, polystyrene nanospheres can be reacted with amine-terminated thiols through the use of a water-soluble carbodiimide and N-hydroxysuccinimide. Fluorescence microscopy was used to image the nanosphere distribution on the surface, from which information on the position and width of the gradient transition was obtained. The gradient center and width were found to depend on the offset potential and magnitude of the applied potential window. The gradient center potential shifts cathodic as the center of the potential window shifts anodic, and the gradient width increases with a decrease in the width of the applied potential window. Since in-plane composition control results in the control of physical properties, the gradient surfaces produced and studied here can be used in applications requiring anisotropy in in-plane chemical or physical properties.