Background: Chromium is one of the most commonly used heavy metals in industry. It is known as a pollutant that its discharge into the environment needs special care. Objectives: The current study aimed to evaluate the functionalized multi-walled carbon nanotubes (f-MWCNTs) as a novel adsorbent of chromium in aqueous solutions. Materials and Methods:The virgin MWCNT was protonated using sulfuric acid as a strong oxidant. The operating conditions such as initial chromium concentration, contact time, adsorbent dosage and pH were evaluated in the adsorption process. A systematic model for chromium adsorption was presented based on the experimental design. Response surface method (RSM), as a mathematical technique, was used for modeling and optimizing considerable parameters. All experiments were performed according to the Standard Methods for the Examination of Water and Wastewater Results: According to the statistical analysis, R 2 (0.998), adjusted R 2 (0.996), prediction R2 (0.906), coefficient of variation (1.38%), and the mean removal efficiency (54.76%) were calculated. Conclusions: The f-MWCNTs can be applied as an adsorbent with excellent properties in the adsorption process. The Efficiency of 61.75% was predicted by the model in the optimum conditions. In the experimental condition an adsorption percentage of 59.44% was obtained.