Abstract: Electroreduction of eriochrome red B was studied by d.c.polarography,differential pulse polarography, and cyclic voltammetry. There appeared three waves(peaks)over pH range of 6.2-12.2. The sum of wave Ⅰ,Ⅱ and Ⅲ is of diffusion controlled, two-electron,and irreversible one.Wave Ⅰ and Ⅲ are of adsorption prewave and post-wave,respectively,From experimental results a mechanism for electroreduction of eriochrome red B was proposed.