In this study, we modified microcrystalline cellulose by cross-linking it with epichlorohydrin to obtain a rapid and efficient adsorbent for the removal of Reactive Blue 4 dye from aqueous solution. Evidences of the cross-linking of the microcrystal-line cellulose were obtained by Fourier transform infrared spectroscopy, X-ray diff raction, Brunauer– Emmett– Teller analysis, thermogravimetric analysis, and scanning electron microscopy. We investigated the eff ects of adsorbent dosage, pH, initial dye concentration, temperature, and contact time on the dye adsorption capacity. The results showed that the adsorption equilibrium time was just 20 min and the maximum adsorption capacity was 69.79 mg/g. The adsorption isotherm data fitted the Langmuir isotherm model well, and the adsorption kinetics data followed the pseudo-second-order kinetic model. The results of the thermodynamic analysis suggest that the adsorption process was spontaneous and exothermic. Recyclabil-ity experiments demonstrated the good reusability of this adsorbent. Electrostatic interaction was found to dominate the adsorption process.