Adsorption performance of chitosan (CS) hydrogel beads was investigated after impregnation of CS with hexadecylamine (HDA) as a cationic surfactant, for the elimination of reactive blue 4 (RB4) from wastewater. The CS/HDA beads formed with 3.8 HDA were the most effective adsorbent. The adsorption capacity was increased by 1.43 times from 317 mg/g (CS) to 454 mg/g (CS/HDA). The RB4 removal increased with decrease in the pH of dye solution from 4 to 9. The isotherm data obtained from RB4 adsorption on CS and CS/HDA are adequately described by Freundlich model (R2 = 0.946 and 0.934, �2 = 22.414 and 64.761). The kinetic study revealed that the pseudo-second-order rate model (R2 = 0.996 and 0.997) was in better agreement with the experimental data. The negative values of �G° (-2.28 and -6.30 kJ/mol) and �H° (-172.18 and -101.62 kJ/mol) for CS beads and HDA modified CS beads, respectively; suggested a spontaneous and exothermic process for RB4 adsorption. © 2015 Elsevier Ltd. All rights reserved.