4-Vinylguaiacol (4-hydroxy-3-methoxystyrene), vanillin (4-hydrolry-3-methoxybenzaldehyde), and vanillic acid (4-hydroxy-3-methoxybenzoic acid) were isolated from distilled and stored model solutions of shochu (MSS) that originally contained only ferulic acid (4-hydroxy-3-methoxycinnamic acid) using a solid-phase extraction technique. These compounds were analyzed by high-performance liquid chromatography (HPLC) with ultraviolet (UV) detection. The amounts of the metabolites converted from ferulic acid was affected by pH, alcohol concentration, and temperature of during storage. The identities of the metabolites were tentatively determined by gas chromatography-mass spectrometry (GC-MS). The results of this experiment suggested that vanillin was formed via 4-vinylguaiacol from ferulic acid, and was then converted to vanillic acid. The pathway of the decarboxylation of ferulic acid appeared to be one of the chemical transformation.