ZEOLITES ARE A CLASS OF POROUS MATERIALS THAT COMPRISE INORGANIC OXIDE ATOMS COVALENTLY LINKED INTO A CRYSTALLINE FRAMEWORK. THE PORE DIAMETERS OF ZEOLITES MEASURE TYPICALLY 5 A TO 10 A AND ARE CONSISTENTLY SIZED BECAUSE OF THE CRYSTALLINE FORMATION. ONE SPECIFIC FAMILY OF ZEOLITES COMPRISES AN ALUMINO-SILICATE FRAMEWORK.THE NATURAL ZEOLITES HAVE ALREADY FOUND EXTENSIVE APPLICATIONS TO THE ENVIRONMENTAL PROBLEMS. THE MOST OF THESE APPLICATIONS ARE BASED UPON THEIR CATION- EXCHANGER PROPERTIES. THE ADSORPTION RESULTS INDICATE THAT THE NATURAL ZEOLITE HAS A LIMITED ADSORPTION CAPACITY FOR REACTIVE AND ANIONIC DYES, BUT IS SUBSTANTIALLY IMPROVED UPON MODIFYING ITS SURFACES WITH POSITIVELY CHARGED MODIFIERS.IN THIS WORK, A NEW SYNTHESIZED CHITOSAN-MODIFIED ZEOLITE EMPLOYED AS AN ADSORBENT FOR REMOVAL OF DIRECT BLUE 131 (DB131) AS AN ANIONIC DYE FROM AQUEOUS SOLUTION. CHITOSAN IS A BIOPOLYMER THAT HAS MANY USEFUL CHARACTERISTICS SUCH AS HYDROPHILICITY, BIOCOMPATIBILITY, BIODEGRADABILITY, AND ANTI-BACTERIAL PROPERTIES. A BATCH SYSTEM WAS APPLIED TO STUDY THE ADSORPTION. THE EFFECT OF EXPERIMENTAL PARAMETERS UPON DYE ADSORPTION WAS INVESTIGATED AND OPTIMAL CONDITIONS WERE OBTAINED. THESE PARAMETERS ARE INITIAL CONCENTRATION OF DR131, PH OF SOLUTION, CONTACT TIME, TEMPERATURE AND PARTICLE SIZE, VOLUME OF SOLUTION, KIND AND AMOUNT OF BUFFER, ADSORBENT MASS, INTERFERING IONS, IONIC STRENGTH. THE POINTS OF ZERO CHARGE (PZC) OF ZEOLITE BEFORE AND AFTER MODIFYING WITH CHITOSAN WERE CALCULATED. THE MAXIMUM ADSORPTION CAPACITY OF MODIFIED ZEOLITE AT PH=2 AND CONTACT TIME OF 75 MINUTES WAS 72.54 MG.G-1. THE EQUILIBRIUM DATA WERE APPLIED TO LANGMUIR, FREUNDLICH AND TEMKIN EQUATIONS. THE ADSORPTION ISOTHERM WAS WELL FITTED WITH LANGMUIR MODEL. THE KINETIC OF REMOVAL METHOD WAS STUDIED USING THE FIRST AND SECOND ORDER EQUATIONS.