Technology, Slovak University of Technology, SK-812 37Bratislava, Slovak RepublicReceived: 14 November 1999 / Accepted: 31 December 1999 / Published: 19 February 2000Abstract: Different types of 3-substituted 4H-4-oxobenzopyrans were prepared by micro-wave irradiation as well as by a classical method. The beneficial effect of microwave irra-diation on the aldol condensation of 3-formylchromones with