4-Vinyl guaiacol (3-methoxy 4-hydroxystyrene) can be obtained by decarboxylation of ferulic acid by the strain Streptomyces setonii ATCC 39116. The formation of this metabolite was favoured by microaerobic conditions and the culture medium employed, increasing progressively the product concentration from 543.3 up to 885.1 mg/l when aeration level was diminished, reaching a highest volumetric productivity of 70.4 mg/l h and a product yield of 1.11 mol/mol. The identity of the metabolite was confirmed by gas chromatography-mass spectrometry. A metabolic study of ferulic acid and the main degradation products (ferulic acid, 4-vinyl guaiacol, protocatechuic acid, vanillyl alcohol, vanillic acid and vanillin) suggested that ferulic acid was the only substrate capable to be transformed into 4-vinyl guaiacol by this strain of S. setonii.