A microcantilever sensor is reported for the trace detection of peroxide vapors. The sensor features a self-assembled monolayer that undergoes chain polymerization in the presence of peroxide radicals, causing a deflection of the cantilever. The generation of radicals using a heated filament, and the resulting surface polymerization reaction, is based on initiated Chemical Vapor Deposition chemistry. The sensor was successfully demonstrated with hydrogen peroxide and exhibited inherent reversibility and a selective, self-amplified response. Air and water were tested as interferents. This trace peroxide detector has industrial applications and addresses an aviation security need for the reliable detection of homemade explosives. (C) 2009 Elsevier B.V. All rights reserved.