The role of metal-support interaction in the hydrogenation of cinchonidine (CD) was studied on acid- and base-doped flame-made Pt/alumina. Analysis of the product distribution revealed that on Pt/alumina and Pt/alumina-silica CD adsorbs on Pt in pro(S) geometry, but doping the support with only 0.25 wt.% Cs2O is sufficient to invert the major adsorption mode to pro(R). The origin of differences between the effect of an acidic additive and support acidity is discussed. (C) 2010 Elsevier Inc. All rights reserved.