Scanning electrochemical microscopy (SECM) and copper staining are combined to achieve visualisation of proteins on surfaces. Proteins are adsorbed on a polyvinylidene fluoride (PVDF) membrane or on a polyethylene terephthalate (PET) surface and stained using a standard protocol involving copper salts. Salts are then reduced to copper and detected by SECM with ferrocene methanol as a redox mediator in aqueous solution. During the SECM scan, the potential is held at a value at which the oxidation of the redox mediator occurs and a positive feedback current is detected when scanning over copper clusters. A negative feedback is observed elsewhere. This method enables unspecific protein adsorption mapping on polymeric membranes and into microchannels without any requirement of enzymatic activity or affinity to a labelled secondary reporter. (c) 2006 Elsevier B.V. All rights reserved.