BACKGROUND: Aqueous two-phase extraction is recognized as an effective, versatile and important emerging green-technique for the downstream processing of biomolecules. Extraction of phenolic compounds from trimmings of Eucalyptus globulus wood veneers was studied using aqueous two-phase systems (ATPS) (water + polymer + salt) based on PEG 2000 and ammonium sulphate. The aim was the recovery of phenolic compounds to be used as natural antioxidants. Experiments were planned to optimize the extraction process. The influence of several operational conditions (time, temperature, ATPS composition, solid-liquid ratio and settlement time) on phenolics recovery was studied. RESULTS: It was found that phenolic compounds have preference for the top PEG-rich phase. Settlement time had no significant impact on phase composition. Total phenols yield increased with temperature, extraction time and amount of solvent used. However, ATPS composition did not significantly influence total phenol yield. Extract analysis by RP-HPLC-ESI-TOF confirmed the presence of phenolic compounds with potential antioxidant activity, namely, mono and digalloyl glucose, (-)-gallic acid, ellagic acid and quercetin 3-O-rhamnoside. CONCLUSION: Results demonstrated that extraction with ATPS (PEG 2000 and ammonium sulphate) is an efficient way for recovering phenolics from eucalyptus wastes without requiring previous purification (total phenols yield of up to 1.88 +/- 0.04 mg GAE/100 o.d. wood). (C) 2013 Society of Chemical Industry