BACKGROUND: Biphasic systems with immiscible solvents have been studied for in situ product removal, and have shown improvements in bioreactor performance, however, problems associated with solvent biocompatibility, bioavailability and operation have been identified. One alternative is the solid-liquid system in which polymer beads are used, absorbing and removing target compounds from the aqueous phase while maintaining equilibrium conditions. This work aims to identify polymer properties that may be important in polymer selection for selected biotransformation molecules including 2-phenylethanol, cis-1,3-indandiol, iso-butanol, succinic acid and 3-hydroxybutyrolactone. RESULTS: Relatively hydrophobic compounds (e.g. 2-phenylethanol) tend to be absorbed by polymers better than hydrophilic ones (e.g. iso-butanol) based on partition coefficient tests; values as high as 80 were obtained for the former and <3 for the latter. Owing to the presenceof polar functional groups on these compounds, polar polymers such as Hytrel (R) performed better than non-polar ones such as Kraton (R). Crystallinity and intermolecular hydrogen-bonding were also found to be important polymer properties. CONCLUSION: Polymers showed excellent results in absorbing hydrophobic compounds such as aromatic alcohols, and positive results in absorbing hydrophilic compounds but to a lesser extent. Grafting hydrophilic functional groups onto polymers may be a promising approach for extending polymer uptake capabilities and is currently being investigated. (C) 2009 Society of Chemical Industry