Chitin is a natural polymer material that is abundant and easy to use at a low cost. In this research, a chitin-based adsorbent, polyethylenimine (PEI)-crosslinked chitin (PEI-chitin), was prepared by crosslinking PEI after binding glutaraldehyde to the specific functional groups of chitin surface. Its adsorption performance on Reactive Black 5 (RB5) was evaluated by batch and fixed-bed column studies. Regeneration study was also conducted to assess the reusability of PEI-chitin. The main results were as follows: pH 2 was optimal for the removal of RB5 from aqueous solution. Langmuir model was better fitted with the isotherm experimental data and the maximum adsorption capacity of RB5 was calculated to be 321.6 mg/g at pH 2. Pseudo-second-order model was better for depicting the kinetic data. The Thomas model can be well adapted to the breakthrough curves. The consecutive adsorption-desorption experiments were performed up to 3 cycles in batch and fixed-bed column systems. The sorption and desorption efficiencies in the batch system were at least 89.1 % and 92.2 %, while the column experiments showed 94.7 % and 97.6 %, indicating high potential in practical large-scale applications.