Rhodium complexes have been tethered to silicate MCM-41 via an amine ligand. X-ray diffraction (XRD) and N-2 adsorption-desorption studies illustrate that the resultant materials maintain the mesoporous structural ordering of MCM-41, but exhibit reduced pore sizes, total pore volumes and BET surface areas. Comparative catalytic studies have been performed of the aminated MCM-41-tethered rhodium complexes and the corresponding untethered rhodium complexes in 1-hexene hydroformylation at 80degreesC and 195-1950 kPa (H-2/CO = 1). The tethered PPh3-free rhodium complex has disadvantage over the corresponding untethered one in catalytic activity and selectivity except for n/i aldehyde ratio. The tethered PPh3-containing rhodium complex has advantage over the corresponding untethered one in catalytic activity and selectivity except for n/i aldehyde ratio. Excess PPh3 added enhances obviously the performances of the tethered PPh3-containing rhodium complex in all aspects. The effects of total reaction pressure and donor ligands on the catalytic properties are dealt with. (C) 2004 Elsevier B.V. All rights reserved.