An efficient Rh/PPh₃ catalyst has been developed for the homogeneous isomerization of 1-alkenes to (E)-2-alkenes. Various alkenes are amenable to the protocol to afford the corresponding (E)-2-alkenes with high yields and good stereoselectivities. In order to address the problem of catalyst separation and recycling, a porous organic polymer supported rhodium catalyst (Rh/POP-PPh₃-SO₃Na) was synthesized for the heterogeneous isomerization of 1-alkenes. The heterogeneous catalyst showed a high activity, stereoselectivity and recyclability. Two possible mechanisms, namely, alkyl and allyl mechanisms, were involved in the olefin isomerization process.