In this study, gum was successfully extracted from tamarind seeds (gum) and used as a material for removal of reactive dye (Reactive Blue 220-RB220). The performance of decolorization and COD reduction of gum was investigated using one-factor-at-a-time method. The factors include pH, mixing time, agitating speed, color concentration, and gum concentration. Under optimal conditions, color and COD removal efficiency of gum was roughly 74.4% and 83.3%, respectively. These results indicate that gum is a “green” and “eco-friendly” coagulant and has great potential for application in textile dyeing wastewater treatment.