The heterogenization of homogeneous catalysts is of critical importance for both fundamental research and practical applications. The key obstacle to industrial applications of heterogenized homogeneous catalysts is the long-term stability of the immobilized molecular complexes. We unambiguously demonstrate in this report that the vinyl-functionalized PPh3 polymers supported single Rh sites (Rh/POL-PPh3) catalyst provided not only excellent catalytic activity but also ultrahigh stability for fixed-bed olefins hydroformylation, which is one of the most important industrial homogeneous catalytic processes for the synthesis of aldehydes and alcohols. HAADF-STEM and EXAFS results indicated that the Rh atoms were present in single Rh sites which were strongly coordinated with the exposed phosphorous atoms of the POL-PPh3 support. The Rh/POL-PPh3 catalyst provided high activity and selectivity because it maintained the catalytic functionalities similar to the homogeneous HRh(CO)(PPh3)(3) complex, as demonstrated both by P-31 MAS NMR and in situ FT-IR experiments. Thus a reaction mechanism, similar to that over the homogeneous HRh(CO)(PPh3)(3) complex, was proposed for olefin hydroformylation over the novel Rh/POL-PPh3 catalyst. (C) 2015 Elsevier B.V. All rights reserved.