An efficient and stable oil/water Pickering emulsion system was constructed for hydroformylation of 1-octene with surface modified mesoporous silica nanospheres as stabilizer and Rh-TPPTS as catalyst. Compared to the neat water-oil biphasic system, the Pickering emulsion system exhibits much higher activity (TOF: 392 h(-1) versus 56 h(-1)) and aldehyde selectivity (79.0% versus 45.7%) in hydroformylation of 1-octene under non-stirring conditions due to the greatly increased interface area. It was found that dimethyloctadecylammonium group is more efficient than octadecyl group for emulsion catalytic system, which is mainly attributed to its enrichment effect for anionic Rh-TPPTS on the interface of two phases. The higher activity and aldehyde selectivity were obtained with mesoporous silica as stabilizer than with nonporous silica, which is attributed to the enhanced diffusion rate of the reactants by the mesopore and uniform distribution of Rh-TPPTS in the mesopore. The Pickering emulsion system could be easily recycled without obvious loss of activity and aldehyde selectivity. (C) 2015 Elsevier Inc. All rights reserved.