Activated alumina (AA) and Iron oxide impregnated on activated alumina (FeAA) by wet impregnation method were investigated in arsenate (As (V)) removal from synthetic water. Box-Behnken Design was utilized to reveal the optimization of FeAA performance to adsorb the toxic pollutant. The result from the pre-test indicated that FeAA provided better percent removal than AA for both arsenite (As (III)) and arsenate (As (V)). Therefore, merely FeAA was further experimented under various conditions obtained from Box-Benhken design. There were 30 analytical sets of FeAA in total conducted in batch tests based on three independent variable that are pH (3, 6 and 9), % Fe loading per alumina (2, 4 and 6%), and initial As (V) concentration (100, 300 and 500 µg/L). The dependent variable was percentage of As (V) removal. The calculation result from Box-Benhken design at 15th minute revealed that the optimal condition was pH of 3, %Fe loading per alumina weight of 2.57 and As (V) initial concentration of 100 µg/L provided the highest percentage removal of 77.64. At neutral pH which is the pH of groundwater, %Fe loading per alumina weight of 4.53 and As (V) initial concentration of 100 µg/L provided the optimal condition with a percentage removal of 62.50, at 15th minute.