The behavior of promazine in 1,2-dichloroethane was Studied using Cyclic voltammetry at the ITIES and UV-vis spectrophotometry. The analysis of voltammograms and spectra obtained varying promazine concentration, pH, nature and concentration of organic electrolyte and applying positive polarisation at the interface allowed us to postulate a reaction scheme consisting in a first step of promazine partition to organic phase, followed by a charge transfer complex (CTC) formation with 1,2-dichloroethane. This CTC induces the oxidation of promazine to the corresponding radical cation which is stabilised in organic phase by pi-mers formation. pi-mers complexes form ion pairs with the anions of the organic base electrolyte. Similar results were found using methotrimeprazine, another phenothiazine derivative, with a methoxyl group attached to the ring. Chlorpromazine, triflupromazine, perphenazine and fluphenazine were stable in 1,2-dichloroethane. (C) 2007 Elsevier Ltd. All rights reserved.