Carbon nanotubes (CNTs) exhausted with dye reactive red 3BS were regenerated by microwave irradiation under N-2 atmosphere. High regeneration efficiency was achieved and the regeneration efficiency reached 92.8% after four cycles regeneration. The decrease in adsorption capacity was suggested to be due to the deposition of decomposition residues in CNT pores, which blocked the carbon porosity and decreased the specific surface area. (C) 2010 Elsevier B.V. All rights reserved.