Dyes are one the most important groups of pollutants which are widely used in industries such as textile, plastics, leather, food, cosmetics and printing. Due to their hazardous nature, the effluent from such industries poses major problems to the environment as well as the human health. Therefore, nowadays, the importance of dye removal from effluents containing textile dyes has become of greater concern. Various removal techniques are used, among which the most effective is adsorption. The main goal of this research is to evaluate walnut shells as a low-cost and agricultural adsorbent for the removal of textile dyes from aqueous solutions. For this purpose, the batch adsorptions of three dyes namely Acid Red 88, Acid Blue 113 and Direct Blue 15 onto walnut shells were investigated. The effect of three most effective factors on dye removal such as the Initial dye concentration in 4 levels (25, 50, 100 and 150 mg/L), adsorbent dosage in 4 levels (5, 10, 20 and 35 g/L) and pH in 3 levels (4, 6 and 8) were evaluated by means of full factorial experiment design. The experiments carried out in this research can be divided into three sections:The first section involves the kinetic experiments (112 tests) which were carried out in order to study the effect of contact time and to determine the equilibrium time of the dye adsorption process for each dye. The solution containing Acid Red 88 reached equilibrium after 90 min of contact with the adsorbent, while the other two dyes reached equilibrium after 120 min. The kinetics analyses were conducted using pseudo-first-order, pseudo-second-order and Elovich models. The results showed that the adsorption of the three dyes studied in the current research, best fit the pseudo-second-order kinetics model. In the second section, adsorption isotherm experiments were conducted and it was found that the maximum adsorption capacity of walnut shells for the removal of Acid Red 88, Acid Blue 113 and Direct Blue 15 is 24.6, 15.4 and 11.3 mg/g, respectively. Furthermore, equilibrium isotherms were analyzed by Langmuir and Freundlich and BET adsorption isotherm models. According to the results, the absorption of these three dyes onto walnut shells can be well described by Freundlich adsorption isotherm model. The third section composes of 288 tests done to evaluate the effect of the three most important chosen factors (Initial dye concentration, adsorbent dosage and pH) in dye removal by walnut shells. Statistical analyses proved that approximately 70% of the data had a removal efficiency percent in the range of 70 to 100 percent. The maximum dye removal efficiency for Acid Red 88, Acid Blue 113 and Direct Blue 15 was reported as follows: 96.6, 96.4 and 87.4 percent. The results obtained of the analysis of variance (ANOVA) determined that the adsorbent dosage has the most contribution to the process of dye removal by walnut shells (49%). The augmentation in the amount of adsorbent considerably increases the dye removal efficiency; while by increasing the initial dye concentration, the removal efficiency slightly decreases. However, the change in the pH of the solutions did not significantly affect the adsorption process.The dye removal efficiency of walnut shells for the 3 dyes was compared to that of activated carbon in the optimum condition. Based on the results obtained, walnut shells have more capacity in removing Acid Blue 113 and Direct Blue 15 in comparison with activated carbon, whereas the adsorbent showed similar results for Acid Red 88. Due the high-cost of activated carbon in relevance with walnut shells, and by taking into consideration its high removal efficiency and availability, therefore walnut shells as an adsorbent, is preferable for the case of these three dyes. Overall, walnut shells with maximum size of 300 microns have the optimal removal efficiency for these Acid Red 88, Acid Blue 113 and Direct Blue 15 at the following lab conditions: initial dye concentration of 25mg/L, Adsorbent dosage of 35g/L, natural pH and contact time of 120 min.