Wells-Dawson type molybdovanadophosphoric heteropolyacids (H6+nP2Mo18-nVnO62) (n = 1-2,4) have proved to be effective catalysts for Prins cyclization between alkenes and paraformaldehyde to produce corresponding 1,3-dioxane derivatives. The effects of solvents, catalysts, reaction-time, reaction-temperature and the ratio of olefin to catalyst were investigated systematically using styrene and paraformaldehyde as model substrates. Compared with conventional catalytic systems, the high-reaction rate, mild conditions, and improved selectivity are the features obtained in our systems. A reasonable mechanism was also proposed. (C) 2004 Elsevier B.V. All rights reserved.