The substrate selectivity and enantioselectivity of Solanum tuberosum epoxide hydrolase 1 (StEH1) have been explored by steady-state and pre-steady-state measurements on a series of styrene oxide derivatives. A prefer-ence for the (S)- or (S,S)-enantiomers of styrene oxide, 2-methylstyrene oxide andtrans-stilbene oxide was established, with E-values of 43, 160 and , respectively.