Water soluble dyes , such as methylen blue, phenazine methosuiphate and other dyes derivatives, have been used as mediators due to their high election transfer efficiency and low cost [1-2]. In the present study the electrochemical properties of aqueous chioropromazine Hydrochloride (an electro active water soluble phenothiazine derivatives) at pH 2-10 were investigated by cyclic Voltammetry at a boron doped diamond ( I3DD ) electrode. A well defined reversible redox couple was observed in acidic solutions [3]. The standard potential and kinetic parameters for chloropromazine 1-lydrochioride were obtained by fitting experimental cyclic voltammograms to those generated by the DigiSim programs .The electrogemated oxidized form of chloropromazine Hydr’ochloride has been used as an efficient organic catalyst for the oxidation of L — cystein , thiouracil , thiocytosine , thiocyanat and sulphide at a BDD electrode immersed in aqueous media [4].The cyclic voltammetry measurements indicate that an electrocatalytic process occurs , where electrochemically generated chloropromazine oxidized species is reduced by sulphur compounds back to the parent chloropromazine species via a .EC’ oxidation mechanism. The determantion of catalytic rate constant (Kat) was accomplished again by fitting experimental cyclic voltammograms with simulated ones [5].