Sulfonic acid group (SO3H)-bearing amorphous carbon/mesoporous silica composites were studied for use as solid acid catalysts. Sugar-derived amorphous carbon with SO3H cannot catalyze hydrophobic acid-catalyzed reactions, such as the dimerization of R-methylstyrene, because of the small surface area. However, SO3H-bearing sugar-derived amorphous carbon supported on mesoporous silica exhibits…