The adsorption of the chiral modifier cinchonidine on platinum in ethanol as a function of temperature has been studied with surface-enhanced Raman spectroscopy (SERS). The temperature range chosen was from 30 to 70degreesC, within which both the activity and selectivity of cinchonidine-modified Pt catalysts have been shown to change dramatically. Platinum surfaces were modified with 260 muM cinchonidine in ethanol, and examined both in pure ethanol and in the modifying solution itself. Adsorbed cinchonidine under pure ethanol was found to partially desorb as the temperature was raised, accompanied by an increase in the average tilt of the quinoline group with respect to the surface. In contrast, the presence of solution-phase cinchonidine resulted in an increase in the cinchonidine surface coverage and average tilt as temperature was raised. In a previous study [J. Mol. Catal. A 212 (2004) 277] we showed that hydrogen causes a dramatic enhancement in the SERS response of adsorbed cinchonidine. This was attributed to a conversion of cinchonidine to 10, 11 -dihydrocinchonidine on the Pt surface and a more flat orientation of the quinoline group. In both pure ethanol and in 260 LM cinchonidine, the presence of hydrogen causes a significant decrease in the alkaloid SERS bands at temperatures above 40degreesC. In addition, the average tilt of the quinoline group increases significantly at these elevated temperatures. The temperature-dependence of 10,11-dihydrocinchonidine adsorption was also investigated, and is almost identical to that observed for cinchonidine in the presence of hydrogen. This lends further support to the conclusion that cinchonidine is being hydrogenated on the Pt surface in the presence of hydrogen. The significant changes observed on the cinchonidine-modified Pt surface above 40degreesC correlate well with reported decreases in enantioselectivity and turn-over frequency at similar temperatures during ethyl pyruvate hydrogenation. (C) 2004 Elsevier B.V. All rights reserved.