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Removing lignin, delignification, is necessary to increase the cellulose and hemicellulose contents. Usually, the conventional of delignification process involves high alkaline (2.5 M) and high temperature (150 °C) conditions. In this work, the delignification of oil palm Empty Fruit Bunch (EFB) was investigated using microwave irradiation at low alkaline concentrations. Further, the effect of adding hydrogen peroxide (H2O2) as a hydroxyl radical source in the delignification process was also evaluated. The delignification of EFB was carried out by adding 7.5 g of EFB/L and 500 ppm of H2O2 in NaOH solution until the total volume of 200 mL. The process was conducted in the microwave with a setting power of 100 Watt for 15 min. The NaOH concentration varied at 0, 0.2, 0.4, 0.6, and maximum at 0.8 M, around 10% of the conventional delignification condition. It was found that the temperature of the solution increased with increasing times of the microwave radiation process. The total suspended solid (TSS) was influenced significantly by NaOH concentration. The addition of H2O2 has less effect on lignin removal. Lignin removal in 0.2 M NaOH without and with H2O2 reached 26% and 27%, respectively. The higher NaOH concentration could penetrate holocellulose so that the lignin percentage increased. The visualization of EFB by SEM proved that delignification proceeded successfully, in which could remove impurities from the surface of EFB. [ABSTRACT FROM AUTHOR]