Here we describe a new microcontact printing technique (mu CP), based on a catalytic reaction between an Fmoc-protected self-assembled monolayer (SAM) of aminothiols chemisorbed on a gold surface and an elastomeric stamp bearing covalently attached piperidine. The elastomeric stamp was used to selectively cleave Fmoc groups from the surface of a SAM on gold in the places of conformal contact. The technique permits nanoscale pattern fabrication with edge resolution less than 50 nm, avoiding problems of conventional microcontact printing associated with diffusion of chemical "ink", and provides a simple method for the chemical modification of SAMs.