Immobilization on silica of selective homogeneous hydroformylation catalysts based on xanthene ligands is reviewed. Various immobilized catalysts are compared, such as SAPC, so]-gel-based catalysts, silica-anchored catalysts used both in an organic phase as well as in supercritical carbon dioxide (scCo(2)), and chemical modifications of silica-anchored catalysts. In all instances, the high selectivity of the homogeneous Xamphos ligands is retained and linear to branched ratios are :20 or higher. Formation of 2-octene from 1-octene via isomerization also remains low (<5%) as in the homogeneous phase. The rates expressed in turnover frequencies drop considerably except for the experiments in scCO(2), which are only half of those in the homogeneous phase. Leaching of rhodium to the product is in all cases below the detection limit of ICP-AES (1 ppm). (C) 2002 Elsevier Science B.V. All rights reserved.