The influence of mass transfer limitations on the enantio- and regioselectivity in hydrogenation of 1-phenyl-1,2-propanedione was studied. Gas-liquid mass transfer limitation as well as liquid-solid mass transfer limitation did not influence the enantio-and regioselectivity of the reaction, compared to the performance of the system under kinetic control. Under various regimes, the enantiomeric excess of the (R)-1-hydroxy-1-phenylpropanone was about 55% and regioselectivity remained at about 10, which makes process scale-up with respect to enantio-and regioselectivity straightforward. (C) 2003 Elsevier Science B.V. All rights reserved.