The adsorption of reactive dyes onto acid-treated palm shell powder (APSP) and chitosan has been investigated. The parameters affecting the rate process involved in the removal of dye like contact time, temperature, pH, adsorbent dose, and dye concentration were studied. pH 4 was suitable for the adsorption of both reactive dyes onto chitosan and was independent of pH in the range pH 2 to 9 using APSP as the adsorbent. The process of dye removal followed pseudosecond-order kinetics. The adsorption equilibria isotherms were analyzed by the Langmuir and Freundlich isotherms. The adsorption capacities were found to be 13.95 mg.g(-1) and 24.86 mg.g(-1) for reactive red 141 and reactive blue 21 using APSP as adsorbent. The adsorption capacities were found to be 22.48 mg.g(-1) and 70.08 mg.g(-1) for reactive red and reactive blue, respectively, using chitosan as the adsorbent.