Background: Textile and dying industries are considered most important industries of each country. In these industries due to the use of different colors in different processes, their wastewater is highly colored and must be treated before discharge to the environment. The objective of this study was Investigation of nano alumina efficiency for removal of Acid Red 18 dye from aqueous solutions. Methods: This study was carried out in the laboratory scales. Synthetic solution was made from Acid Red 18 dye stock and effect of different parameters such as dye concentration, pH solution, nano alumina concentration and contact time on dye removal efficiency were evaluated. Also kinetic and isotherm models of adsorption process were evaluated. Results: Results from experiments showed that dye removal was increased with increasing contact time and nano alumina powder concentration, while decreased with increasing of pH and dye concentration. Experimental data were best fitted to Longmuir isotherm model (r2=0.994). The maximum adsorption capacity for Acid Red 18 was found 83.33 mg g-1. The results from kinetic studies showed that removal of Acid Red 18 was best described by pseudo-second order kinetic model (r2=0.999). Conclusion: The present study shows nano alumina powder is promising adsorbent for removal of Acid Red 18 from aqueous solution.