Preparation of a biopolymer chitosan-polypropylene imine (CS-PPI) as a biocompatible adsorbent and its reactive textile dyes removal potential were performed. Chemical specifications of CS-PPI were determined using Fourier transform infrared, H-1-NMR, and C-13-NMR. The surface morphology of the CS-PPI surface was characterized by scanning electron microscopy. Results confirmed that the linkages between the NH2 groups of PPI dendrimer and carboxylic groups of modified Chitosan were accomplished chemically. Two textile reactive dyes, reactive black 5 (RB5) and reactive red 198 (RR198), were used as model compounds. A response surface methodology was applied to estimate the simple and combined effects of the operating variables, including pH, dye concentration, time contact, and temperature. Under the optimal values of process parameters, the dye removal performance of 97 and 99% was achieved for RB5 and RR198, respectively. Furthermore, the isotherm and kinetic models of dyes adsorption were performed. Adsorption data represented that both examined dye followed the Langmuir isotherm. The adsorption kinetics of both reactive dyes were satisfied by pseudo-second order equation. Based on this study, CS-PPI due to having high adsorption capacity (6250 mg/g for RB5 and 5882.35 mg/g for RR198), biocompatibility and ecofriendly properties might be a suitable adsorbent for removal of reactive dyes from colored solutions. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 127: 2607-2619, 2013