Numerous technologies have been used to reclaim valuable chemicals from bio-oil. In this study, a combination of the basification-acidification process and column chromatography was employed for the separation of high-purity syringol and acetosyringone from rice straw-derived bio-oil. The optimal conditions for the basification-acidification process and the possible precipitation mechanism of the basification were explored. The results showed the following as the optimal conditions for the basification process: mass ratio of calcium hydroxide (Ca(OH)(2)) to bio-oil, 2.0; reaction temperature, 70 degrees C; and reaction time, 30 min. The results also showed that 1.6 mol of hydrochloric acid (HCl) per gram of bio-oil was optimal for the acidification. The precipitation was found to proceed via a possible mechanism involving the reaction of the phenolic compounds in the bio-oil with Ca(OH)(2) to produce a precipitate. After further separation by column chromatography, purities of 91.4 and 96.2% (from gas chromatography-mass spectrometry) were obtained for syringol and acetosyringone, respectively. Their recoveries for the whole process were 73.0 and 39.3%, respectively.