In the present paper, the molecular weight distributions (MWDs) of Baker's yeast wastewater (BYW) during electrocoagulation (EC) are investigated by High Performance Size Exclusion Chromatography (HPSEC) with ultraviolet diode array (DAD) and refractive index detectors (RID). The results of this study show that using DAD and RID in HPSEC are quite useful in order to reveal changes in MWDs of all components (whether UV-Vis absorption or not) by RID, and colored (strongly absorb UV-Vis radiation) by DAD. Molecular Weights (MW) of components are varied in a wide range of 92.0 Da - 2.1x10(6) Da. The high molecular weight components (HMWCs) and low molecular weight components (LMWCs) are present in low concentrations but they contribute high amount to color intensity (total contribution of two fractions are about 80%) whereas the intermediate molecular weight components (IMWCs) have high concentration with low amount to color intensity. The optimum operating conditions for the removal of color and COD are found as 86% and 43% at 80 A/m(2), pH(i) 4 and 20min in EC process with Al electrode. The EC process remove the HMWCs more efficiently; thus color removal efficiencies are high with respect to COD and TOC removal efficiencies during EC.