A controllable assembly technique of [Ru(bpy)(2)IP]3(+/2+) (where bpy = 2,2'-bipyridine and IP=imidazo[4,5,f][1,10]phenanthroline) promoted by calf thymus DNA at an ITO electrode is proposed. The stable assembled layer containing [Ru(bpy)(2)IP](3+/2+) ad double stranded DNA is obtained on the ITO electrode using repetitive voltammetric sweeping, confirmed by ex situ voltammetry, X-ray photoelectron spectroscopy (XPS) and the inverted fluorescence microscopy. There exist two pairs of diffusion-controlled waves and two pairs of prewaves for [Ru(bpy)(2)IP](2+) in the voltammetric sweeping process. The half-wave potentials of the prewaves are far more negative than those of the diffusion-controlled waves. These experimental results suggest that double stranded DNA is enable to accelerate and increase the controllable assembly of Ru(bpy)(2)IP](3+/2+) by using the ITO surface. The fluorescence microscopy imaging reveals that [Ru(bpy)(2)IP](3+/2+) has the ability to bind with double strand DNA. The fluorescence intensity of [Ru(bpy)(2)IP](3+/2+) with DNA is stronger than that without DNA. (c) 2005 Elsevier Ltd. All rights reserved.