The effects of the addition of pivalic acid to the reaction media on the hydrogenation rate and the enantio-differentiating ability (e.d.a.) for the hydrogenation of 2-octanone were studied over an (R,R)-tartaric acid-NaBr-in-situ-modified nickel catalyst. It was revealed that the modification with both tartaric acid and NaBr was necessary for increasing the e.d.a. by the addition of pivalic acid to the reaction media. The role of pivalic acid in the enantio-differentiating hydrogenation of 2-octanone was different from that of acetic acid in the hydrogenation of methyl acetoacetate.