In this study, salt fractionated bitter gourd (Momordica charantia) peroxidase was used for the decolorization of water-insoluble disperse dyes; Disperse Red 17 and Disperse Brown 1. Effect of nine different redox mediators; bromophenol, 2,4-dichlorophenol, guaiacol, 1-hydroxybenzotriazole, m-cresol, quinol, syringaldehyde, violuric acid, and vanillin on decolorization of disperse dyes by bitter gourd peroxidase has been investigated. Among these redox mediators, 1-hydroxybenzotriazole was the most effective mediator for decolorization of both the dyes by peroxidase. Bitter gourd peroxidase (0.36 U/mL) could decolorize Disperse Red 17 maximally 90% in the presence of 0.1 mM 1-hydroxybenzotriazole while Disperse Brown 1 was decolorized 65% in the presence of 0.2 mM 1-hydroxybenzotriazole. Maximum decolorization of these dyes was obtained within 1 h of incubation at pH 3.0 and temperature $40^{circ}C$. The application of such enzyme plus redox mediator systems may be extendable to other recalcitrant and water insoluble synthetic dyes using novel redox mediators and peroxidases from other new and cheaper sources.