The adsorption of Fast Green (FG) dye on pristine multi-walled carbon nanotubes (CNTs) was investigated in this study. The adsorption was carried out under different operating conditions. The operating conditions were contact time, adsorbent dosage, initial dye concentration, the pH of the solution and temperature. The analysis of results found that the removal percentage of FG dye on CNTs decreases with increase in initial FG concentration. It was found that the increasing of CNTs dosage enhanced the efficiency of dye removal. It was also found that the increasing of temperature significantly enhanced the removal percent of FG dye and it is indicated that the adsorption of FG dye on CNTs was in endothermic nature. The study reports that the best pH of solution for the adsorption of FG on CNTs were 4. The adsorption data have been analyzed using Langmuir and Freundlich. Fitting the equilibrium adsorption data by Langmuir and Freundlich models shows that experimental data well explained by the Langmuir equation.