We report the enantioselective hydrogenation of alpha,beta-unsaturated acid catalyzed by Pd nanoparticles in carbon nanotubes (CNTs) taking the advantage of the channels as nanoreactors. The Pd nanocatalyst inside the channels of CNTs shows higher activity and enantioselectivity than that of Pd nanocatalyst outside the channels. As high as 92% enantioselectivity is achieved. The enhanced catalytic performance is attributed to the enrichment of reactant, chiral modifier, and additive in the channels of CNTs. This work demonstrates the unique feature of CNTs as nanoreactors for asymmetric catalytic reactions. (C) 2013 Elsevier Inc. All rights reserved.