COLORS ARE ORGANIC COMPOUNDS WITH A COMPLEX, TOXIC, CARCINOGENIC, MUTAGENIC AND NON-DEGRADABLE BIOLOGICAL STRUCTURE AND ONE OF THE MOST IMPORTANT WASTEWATER POLLUTANTS IN TEXTILE INDUSTRIES. THIS STUDY WAS CARRIED OUT WITH THE GENERAL PURPOSE OF EVALUATING THE USE OF CHITOSAN /MONTMORILLONITE NANOCOMPOSITE ADSORBENT IN REMOVING ORANGE II FROM INDUSTRIAL WASTE WATER. CHITOSAN/MONTMORILLONITE IS A MODIFIED MONTMORILLONITE TO OBTAIN CHITOSAN/MONTMORILLONITE NANOCOMPOSITE (CTS/MMT) WHICH THE SODIUM IONS IN MONTMORILLONITE LAYERS ARE REPLACED BY CHITOSAN. NANOCOMPOSITE WAS CHARACTERIZED BY SCANNING ELECTRON MICROSCOPY (SEM) TO EVALUATE THE MORPHOLOGY. ADSORPTION EXPERIMENTS WERE PERFORMED AT ROOM TEMPERATURE IN BATCH SYSTEM. THE EFFECTS OF PH, INITIAL CONCENTRATION OF DYE, CONTACT TIME AND ADSORBENT DOSE WERE CONDUCTED. OPTIMIZATION OF ADSORPTION WAS CARRIED OUT BY THE SOLUTION PH RANGED FROM 3-11, THE INITIAL DYE CONCENTRATION RANGED FROM 20-60 MG/L, ADSORBENT DOSE RANGED FROM 0. 1-0. 9 G/L AND CONTACT TIME RANGED FROM 1-3. 5 HOURS. UNDER THESE CONDITIONS, OPTIMAL VALUES OF PH SOLUTION, INITIAL CONCENTRATION OF DYE, ADSORBENT DOSE AND CONTACT TIME FOUND AT 5, 50 MG/L, 0. 7G/L AND 3 HOURS, RESPECTIVELY. THE RESULTS OF THE FITTING OF CONSTANT EQUILIBRIUM DATA ON LANGMUIR AND FREUNDLICH ISOTHERM MODELS SHOWED THAT THE ADSORPTION OF ORANGE II ON THE CTS-MMT WAS CONSISTENT WITH THE TWO ABOVE-MENTIONED ISOTHERMS. THE CORRELATION COEFFICIENT IN BOTH FREUNDLICH AND LANGMUIR MODELS WAS THE HIGHEST (99%), WHICH INDICATES THE BETTER FIT OF BOTH MODELS TO DESCRIBE THE ORANGE II COLOR ABSORPTION ON THE CTS-MMT. ALSO, PSEUDO SECOND-ORDER MODEL WAS FOUND TO AGREE WELL WITH EXPERIMENTAL DATA (R2>0. 99).