The applications of alumina-based adsorbents have popularized in recent years because of their unique characteristics and their potential to remove organic as well as inorganic pollutants from wastewater. Alumina-based composites are considered the most efficient adsorbents. This chapter explains the synthesis of alumina-based adsorbents and their modification to increase the uptake efficiency of water pollutants. Characterization of the adsorbents is discussed to obtain an idea about the composition, texture and the physicochemical properties. Moreover, this chapter briefly describes the interaction and reactivity of the adsorbents with the inorganic and organic water contaminants. Finally, the high regenerative property of alumina-based adsorbents further makes them more environment-friendly to be used in wastewater technology as discussed in this study.