The enantioselective hydrogenation of 2-ethyl-propenoic acid over Pd/alumina modified with cinchonidine has been studied. The reaction, carried out in a batch reactor at 1 bar hydrogen pressure and room temperature, revealed that the isomerization of the C=C double bond is a competing side reaction. Double-bond migration and the subsequent hydrogenation of the two isomer alkenoic acids lowered the enantioselectivity drastically due to the formation of opposite enantiomers.