Oxidative addition of the Co-C bond of Co(eta(3)-CH2CHCHR)(CO)(3) (R = Ph (2a), Me (2b)) to Pt(styrene)(dppe) (1) gives (dppe)(mu-eta(1):eta(2)-RCH=CHCH2)Pt-Co(CO)(3) (R = Ph (3a), Me (3b)). The E-isomer of 3b showed fluxionality due to a site exchange process between the allyl carbon and Co at Pt and complete E-selective allyl transfer reaction from platinum to cobalt, which was accelerated by addition of acrylonitrile or PPh3 whereas the Z-isomer had a rigid structure and showed lower reactivity.