New supported rhodium(I) catalyst precursors were obtained in reaction of [Rh(OMe)(cod)](2) with polymeric monoliths containing methyl-imidazolium moieties and applied in 1-hexene hydroformylation at 10atm of CO/H-2. Under solventless conditions with a small amount of P(OPh)(3) as a modifying ligand, [P(OPh)(3)]/[Rh]=2, ca. 80% of aldehydes with a high n/iso ratio of ca. 6 was obtained in eight successive runs. When P(OCH2CF3)(3) was used instead of P(OPh)(3), n/iso ratios up to 49.8 were obtained, however, the systems were active only in two subsequent reactions. With PPh3 as a modifying ligand, the yield of aldehydes decreased to ca. 20% already in the third run and n/iso was ca. 3. (C) 2009 Elsevier B.V. All rights reserved.