Development of highly efficient, low cost adsorbents for heavy metal ion removal from wastewater is an enduring undertaking. Two major groups of nanocomposite adsorbents are reviewed here. The magnetic carbon family is first discussed including the preparation of such materials. Various carbon sources have been used in the preparation, and the structural characteristics have been analyzed. Cr(VI) removal studies unveil a wide range of performance. The second group adsorbents is polymer functionalized nanocomposites. One notable polymer is polyaniline which is a redox polymer. The redox nature allows the composite materials to facilitate Cr(VI) reduction to Cr(III) which is prone to precipitate under neutral pH condition. The studies show that polyaniline can be feasibly synthesized in situ to cover the support surface, while the support provides mechanical strength and suitable surface area for Cr adsorption. A similar approach is the in situ synthesis of poly(acrylic acid) in the presence of support materials. This group of materials have been applied in Pb(II) removal and the performance is analyzed.