The objective of our study was to compare the reactivity of coniferyl alcohol and ferulic acid with ozone at acidic pH in terms of ozone demand and byproducts formation. Both structures exert an ozone demand of about two moles of ozone per mole of initial compound. Similar ozonation byproducts were identified using gas chromatography/mass spectrometry analysis. Using a low ozone dose (below the ozone demand), byproducts were principally aromatic structures, with vanillin, 3,4-dihydroxy-5-meth-oxybenzaldehyde and vanillic acid as the main compounds. Applying a higher ozone dose (above the ozone demand), furan structures were produced. A reaction mechanism is suggested to explain the formation of such structures. A quantitative study showed that coniferyl alcohol was a stronger precursor of vanillin and vanillic acid than ferulic acid.