A broadband variant of cavity enhanced absorption spectroscopy has been demonstrated at visible wavelengths using red and green light emitting diodes. The broadband CEAS spectrum of a mixture of molecular oxygen and water vapour has been recorded with a bandwidth of 60 nm centred at 675 nm. Quantitative amounts of three atmospherically important absorbers (NO3, NO2 and I-2) have also been retrieved from broadband CEAS spectra of laboratory samples at high dilution using spectral fitting techniques adapted from differential optical absorption spectroscopy. (C) 2004 Elsevier B.V. All rights reserved.