The effects of a co-modifier and carboxylic acid on the hydrogenation rate and the enantio-differentiating ability (e.d.a.) were studied for the hydrogenation of 2-octanone and methyl acetoacetate over a tartaric acid modified reduced nickel catalyst. For the hydrogenation of 2-octanone, tartaric acid, pivalic acid, and Na+ were necessary for the appearance of the predominant e.d.a. Sodium pivalate, instead of the typical co-modifier, NaBr, was appropriate for the in situ modification of reduced nickel. The use of sodium pivalate resulted in a higher hydrogenation rate and e.d.a. (C) 2008 Elsevier B.V. All rights reserved.