The interaction of aqueous solutions of optically pure alanine (AL) with samples of an 11.9% (w/w) Ni/SiO2 catalyst, prepared by homogeneous precipitation/deposition, has been examined, and the resultant modified catalysts were used to promote the asymmetric hydrogenation of a prochiral beta-keto ester (methyl acetoacetate) to a beta-hydroxy ester ((R)-(-)-methyl-3-hydroxybutyrate). The dependence of the level of AL adsorption from the liquid phase on the duration and temperature of the treatment and on the initial concentration of AL in solution was studied. The adsorption of AL on the surface nickel is corrosive and data on the extent of nickel dissolution are provided. The build up of AL on the active surface is graphically illustrated and is related to the observed enantioselectivities; an optimum active surface coverage in the range 0.6-0.8 is identified. Modification of the catalysts with AL not only induced enantioselectivity but also increased the apparent reaction rate. The nature of the interaction of AL with the surface nickel is considered and the catalytic consequences are discussed. Data on catalyst modification by the adsorption of tartaric acid are also included for comparative purposes.