Structurally well-defined ordered mesoporous carbon (OMC)-supported uniform and specifically size-controlled Rh nanoparticle (NP) catalysts with low Rh content were prepared by three different methods (polyol, organometallic, and sonochemical) for higher alcohol synthesis from syngas. During the reaction, the size-confined Rh NPs in OMC were uniformly sintered, and the size of the aggregated Rh NPs was within the optimum metal size range for syngas-to-alcohol (STA) reaction. The catalytic reactions and TEM analyses clearly show that the uniform Rh NPs with a specific size in the OMC supports increase the STA catalytic performance by enhancing the CO insertion and reducing methane formation. Moreover, additional chain growth reactions for the synthesis of C-3 and C-4 alcohols could be produced by the use of uniform Rh nanoparticles on OMC supports. (C) 2015 Elsevier Ltd. All rights reserved.