The use of a cyclodextrin induced inclusion complex can be very useful during the biohydrolysis of poorly soluble substrates. By using hydroxypropyl-p-cyclodextrin (HPB), the water solubility of styrene oxide (SO) was increased seven-fold (from 2.12 to 15.11 g/l at 15 degrees C) (20%, w/v) and at 10% (w/v) HPB SO was almost three times (9.71 g/l at 15 degrees C) more soluble than in 10% dimethylsulfoxide (DMSO) (w/v) (3.8 g/l at 15 degrees C). Increasing concentrations of HPB did not influence the enzymatic stability of epoxide hydrolase (EH) from Rhodotorula glutinis contrary to the organic co-solvents which negatively influenced it in the order DMSO > dimethylformamide (DMF). HPB does, however, negatively influence the EH activity of the biocatalyst R. glutinis UOFS Y-0653. When compared to the inhibition resulting from the addition of organic co-solvents, the inhibition was in the order DMF > HPB > DMSO. Inactivation constants of, 4.54 +/-0.32, 3.29 +/- 0.28 and 1.81 +/- 0.13 (weight ratio 1 w/v) were determined for DMF, HPB and DMSO, respectively. Neither DMSO nor DMF influenced the selectivity of the reaction while HPB decreased it slightly. Thermal studies yielded inactivation energy (E-a) values of 84.0, 82.3 and 86.0 kJ/mol for DMSO, DMF and HPB, respectively. (c) 2006 Elsevier Inc. All rights reserved.