The polarographic and voltammetric reduction of the azo dye 4-nitro-3＇-tert-butyl-4＇-hydroxyazobenzene in Britton-Robinson Buffer with the pH range between 3 and 12 at room temperature has been investigated in aqueous-ethanol solutions of ratio 1:1. Two straight lines were obtained from the E(p) -pH plots for the compound. Diffusion controlled reduction behaviour was observed in acidic and alkaline media hut the products were different. An electron reaction mechanism for the azo compound has been suggested.