Bronsted acidic ionic liquid 1-butyl-3-methylimidazolium hydrogen sulphate [bmim]HSO4 has been demonstrated as an efficient reusable catalyst and solvent, for halogenation of aromatic and aliphatic alcohols in conjunction with microwave and thermal heating. Use of microwave energy not only accelerates the reaction rate, but also provides enhanced yields. Moreover, anhydrous ionic liquid facilitates nucleophilic attack of halide ions on alcohols, thus indicating the enhancement in their nucleophilic character. Easy work up, good yields and facile regeneration of the ionic liquid further increases the scope of the developed methodology. (C) 2008 Elsevier B.V. All rights reserved.