The kinetics and thermodynamics of adsorption of disperse yellow (DY42) by bentonite and organo- modified-bentonite was studied. The organo-modified bentonite was synthesized by bentonite and tetra butyl ammonium iodide (B/TBAI). The B/TBAI was characterized by FT-IR, XRD, SEM, and elemental analysis. The adsorption experiments were carried out to investigate the factors that influence dye uptake by the adsor- bents, such as the contact time under agitation, adsorbent dosage, initial dye concentration, and pH. The exper- imental results show that the percentage of dye removal increases with the increasing the amount of sorbent. Adsorption was pH-dependent. The equilibrium data were fitted to Langmuir and Freundlich isotherms and the equilibrium adsorption was best described by the Langmuir isotherm model. The experimental data fitted very well with the pseudo-first-order kinetic model. The thermodynamic study of the adsorption process showed that the adsorption of DY42 onto B-TBAI adsorbent was carried out spontaneously and the process was endothermic in nature.