The study examined the usefulness of a Fenton-like system for the degradation of ionic liquid residues in water. The ionic liquid was oxidized in a dilute aqueous solution of 1-butyl-3-methylimidazolium chloride (bmimCl). The ionic liquid decomposes readily and rapidly in aqueous solution by chemical degradation in a Fenton-like system. Under chosen conditions the initial bmimCl solution was reduced by a factor of 0.973 within 90 min. Additional results showed that bmimCl degradations in a Fenton-like system in excess H2O2 could be interpreted as a combined oxidation-reduction mechanism. Preliminary investigations of the mechanism of such degradations have indicated that initial OH center dot radicals can attack any one of the three carbon atoms on the imidazolium ring. The intermediates of this reaction may be mono- di- or amino- carboxylic acids. (C) 2007 Elsevier B.V. All rights reserved.