In this study, HA removal by electrocoagulation (EC) using Aluminum (Al) electrodes was evaluated based on Al species and HA was characterized to investigate the HA removal mechanisms. Results showed that Al electrodes were better than Fe electrodes, wherein Al flocs were found to be positively charged by which the negatively charged HA can be attracted. HA removal was 88.9% at 10 min and 91.3% at 20 min, at the initial pH of 4.5 and 6.5, respectively. The Ferron analysis showed that the formation of monomeric Al species (Ala), medium polymer Al species (Alb), and colloidal or solid Al species (Alc) was dependent on initial pH and current density (CD). At higher pH, higher concentration of colloidal or solid Al species (Alc)wasobserved. At higher CD, the HA removal was faster than at low CD, and Alcspecie in the floc was dominant. The spectroscopic analysis of the residual soluble HA showed the preferential removal of highly condensed structures of HA, regardless of CD. The results in this study showed that Alb and Alc, especially Alc, contribute much to the HA removal and that the highly conjugated moieties of HA are readily removed by EC. Specific UV absorbance (SUVA) analysis reveals that aromatic compounds were decreased by the oxidation at the anode. Size exclusion chromatography reveals that high molecular weight (MW) fractions were preferentially removed by EC than the low MW component.