We report development of ZSM-5 nanocatalyst including Fe promoter for decolorization of Reactive Red 120 (RR120) azo dye in a heterogeneous electro-Fenton reaction. The nanocatalysts were characterized by XRD, FT-IR, FE-SEM, N-2 adsorption-desorption and NH3-TPD techniques. The influence of different parameters (Fe percentage, nanocatalyst loading and pH level) on the decolorization efficiency are studied. The results show that the optimum operational conditions are 1% Fe impregnation, 0.1 g nanocatalyst loading and pH 3.0 which result in the highest RR120 decolorization efficiency (ca. 98%). A pseudo-first order kinetic model fits the experimental data with the high correlation factor (R-2 > 0.98). The developed nanocatalyst is a reusable catalyst for the RR120 decolorization which significantly recovers the active sites through regeneration process and provides the high decolorization efficiency ( > 95%) in several batches. The results confirm the high capacity of developed ZSM-5 nanocatalyst for the dye decolorization in commercial scale.