Adsorptive removal of cationic brilliant green (BG) dye by dodecyl-benzene-sulfonic-acid doped polyaniline/multiwalled carbon nanotubes composite has been investigated as a function of contact time, solution pH, initial dye concentration, and temperature. Raman spectroscopy, Fourier transforms infrared spectroscopy, scanning electron microscopy, and X-ray spectroscopic analyses were performed to confirm the BG adsorption. The adsorption of BG was highly selective at pH 3. The adsorption kinetics, isotherms, and thermodynamics were investigated, and equilibrium adsorptions were well-described by pseudo-second-order kinetic and Langmuir isotherm model, respectively, and maximum monolayer adsorption capacities were found to be 434.78, 454.54, and 476.19 mg/g at 30, 40, and 50 degrees C, respectively. The thermodynamic parameters suggested that the adsorption process was spontaneous and endothermic in nature. The magnitude of free enthalpy changes (Delta H degrees) was found to be 31.219 kymol, which revealed that physical forces were involved in the adsorption process.