Carbon nanotubes have attracted great interest in multidisciplinary study since their discovery. Herein, radionuclide 243Am(III) sorption to uncapped multiwall carbon nanotubes (MWCNTs) was carried out at 20+/-2 degrees C in 0.01 and 0.1 M NaClO4 solutions. Effects of 243Am(III) solution concentration, ionic strength, and pH on 243Am(III) sorption to MWCNTs were also investigated. The sorption is strongly dependent on pH values and weakly dependent on the ionic strength in the experimental conditions. The results show that MWCNTs can adsorb 243Am(III) with extraordinarily high efficiency by forming very stable complexes. Chemisorption or chemicomplexation is the main mechanism of 243Am(III) sorption on the surface of MWCNTs. MWCNTs can be a promising candidate for the preconcentration and solidification of 243Am(III) or its analogue lanthanides and actinides from large volumes of aqueous solution, as required for remediation purposes, and perhaps also as a sorbent for the removal of heavy metal ions from the industry wastewater.