Heteropoly acid phosphomolybdic acid (H3Mo12O40P) has been found to be an excellent catalyst for aza-cope rearrangement of N-allylanilines. Various organic solvents and ionic liquids were tested as reaction media. Better results were obtained in ionic liquid reaction media in terms of reaction time and yield of the product. Catalyst could be efficiently recovered from the reaction and reused with negligible loss of catalyst activity even after two cycles. Short reaction time, ambient conditions, simple workup and high yield are some of the striking features of the present protocol. (C) 2009 Elsevier B.V. All rights reserved.