The impact of perchlorate ions and acetonitrile medium on copper redox couple was investigated. The acetonitrile solvent and perchlorate ions were found to synergistically increase the redox potential of Cu(II)-Cu(I) couple, thereby increasing its ability to oxidize more systems and expand the copper redoxi metric analysis window. The difference in the behavior of thiourea towards copper(II) salts in aqueous and non aqueous media was also explored. Based on the synergistic effect, an electroanalytical method for com position analysis of copper(I) thiourea complexes was proposed. Kinetic and quantum chemical studies have been used for mechanistic insight into synergistic effect of acetonitrile and perchlorate ions on copper redox couple.