The rapid assembly of magnetic carbon nanotubes is mediated through the electrostatic attraction of alpha-haematite nanoparticles to carboxylic groups decorating their outer surface. The system is then stabilised through covalently bonding a silica coat using a 3-aminopropyltriethoxysilane precursor, which creates a thin barrier protecting the alpha-haematite particles from aggressive pH solutions. The nanocomposites can be effectively dispersed in aqueous solution and can be attracted to an external magnetic field. The proposed method can be used for synthesis of magnetic CNTs suitable for assembling densely packed magnetic arrays, remotely guided drug delivery and organic chemical wastewater remediation with the added benefit of nanomaterial recovery. Therein, p-nitroaniline was demonstrated to still adsorb to uncoated areas of the silica-sheathed magnetic MWCNT composite. (c) 2011 Elsevier B.V. All rights reserved.