Electrochemiluminescence (ECL) is often used for high sensitivity detection. We describe a new approach to collecting the ECL signal, by coupling of the excited state of [Ru(bpy)(3)](2+) with the surface plasmons in a thin gold film. The energy then radiates into the substrate at a defined angle. Surface plasmon-coupled ECL promises to be useful in chemical and biological assays. (C) 2004 Elsevier B.V. All rights reserved.