The adsorption of Reactive Red 33 dye from aqueous solution onto light expanded clay aggregate (LECA) in a batch mode, fixed-bed reactor has been investigated. The adsorption studies were determined as a function of dye initial concentration, pH, flow rate, temperature, and adsorbent size using response surface methodology. The maximum amount of dye removal (85.11%) was obtained in the optimized conditions (pH = 2, C 0 = 20 mg/L, and T = 20 C; flow rate: 40 L/min and smaller size of LECA granules). Also, highfrequency ultrasound waves have been applied for desorption process which improved the desorption efficiency by 81%. Equilibrium data are fitted well with Langmuir isotherm model and obeyed the Weber-Morris and external diffusion kinetic models. The exothermic nature and negative amount of Gibbs free energy change confirmed the spontaneous nature of this process. The maximum adsorption capacity, q max , as estimated by Langmuir isotherm model was 1.363 mg/g.