We report the synthesis and catalytic application of thermally robust gold nanoclusters formulated as Au-99(SPh)(42). The formula was determined by electrospray ionization and matrix-assisted laser desorption ionization mass spectrometry in conjunction with thermogravimetric analysis. The optical spectrum of Au-99(SPh)(42) nanoclusters shows absorption peaks at similar to 920 nm (1.35 eV), 730 nm (1.70 eV), 600 nm (2.07 eV), 490 nm (2.53 eV), and 400 nm (3.1 eV) in contrast to conventional gold nanoparticles, which exhibit a plasmon resonance band at 520 nm (for spherical particles). The ceria-supported Au-99(SPh)(42) nanoclusters were utilized as a catalyst for chemoselective hydrogenation of nitrobenzaldehyde to nitrobenzyl alcohol in water using H-2 gas as the hydrogen source. The selective hydrogenation of the aldehyde group catalyzed by nanoclusters is a surprise because conventional nanogold catalysts instead give rise to the product resulting from reduction of the nitro group. The Au-99(SPh)(42)/CeO2 catalyst gives high catalytic activity for a range of nitrobenzaldehyde derivatives and also shows excellent recyclability due to its thermal robustness. We further tested the size-dependent catalytic performance of Au-25(SPh)(18) and Au-36(SPh)(24) nanoclusters, and on the basis of their crystal structures we propose a molecular adsorption site for nitrobenzaldehyde. The nanocluster material is expected to find wide application in catalytic reactions.