Cyclic voltammetric behavior of a nonionic surfactant, alpha-(anthraquinonyloxyhexyl)-omega-hydroxy-oligo- (ethylene oxide), ACPEG, has been studied in detail in aqueous media with NaCl as the supporting electrolyte. Attempts have been made to correlate the electrochemical responses with the dissolved states of the surfactant. The shapes of the cyclic voltammograms at a glassy carbon electrode have proved to be fairly dependent on the concentration of ACPEG and on the redox state of the anthraquinone group. Below the critical micelle concentration (cmc), the cyclic voltammogram (v = 10 mV/s) corresponds to the surfactant molecules adsorbed onto the electrode surface. The adsorption of ACPEG molecules at the electrode surface is very weak in nature owing to its low surface activity. A high cmc value and weak adsorption allow diffusion of the monomeric species prior to the reduction to contribute to the total current even below the cmc. At concentrations higher than the cmc, the diffusion-controlled waves are superimposed on the surface waves, and far above the cmc, the voltammetric shape is of a typical diffusion-controlled species. Above the cmc, self-association of ACPEG results in the formation of micellar aggregates, which diffuse to the electrode surface to dominate the adsorption wave. The redox process is influenced by the formation of a quinhydrone-like charge transfer complex. The cyclic voltammetrically determined apparent diffusion coefficient of the micellar solutions changes continuously with concentration; with decreasing concentration the apparent diffusion coefficient approaches the monomeric diffusion coefficient while with increasing concentration it approaches the micellar value. This has been interpreted in terms of change in the diffusion species by dissociation of the micelles formed above the cmc to monomers in the concentration gradient in the diffusion layers. The formation and dissociation reaction can be reversibly controlled by a change in the redox state. A CEC mechanism with the electrochemical reaction coupled with the preceding disruption reaction of the micelles (CE) and the following protonation reaction of the reduced state (EC) has been inferred.