F region strong sunward ion flow embedded in the duskside cell of expanding polar cap ion convection and coincidental increase in the ion temperature were observed from about 73° to 69° in geomagnetic latitude between 16:00 and 16:48 MLT on 19 August, 2006 from an experiment using the European Incoherent Scatter (EISCAT) radars at Tromsø, Sodankylä and Longyearbyen together with the CUTLASS HF radars. The spatiotemporal structure of the convection map obtained by the SuperDARN HF radars showed that the high-speed flow channel elongated in 14–17 MLT was moving equatorward. The flow channel appeared during an interval of negative interplanetary magnetic field B_z associated with large positive B_y. In order to evaluate ion frictional heating and resultant ion temperature increase quantitatively, the experiment was conducted to estimate the ion velocity vector and the ion temperature at the common scattering volume of the EISCAT radars. While the flow channel moved equatorward, the ion temperature increase became less evident at higher part of latitudes within the flow channel, which means that ion frictional heating was depressed where the neutral gases had already responded to the high-speed ions. The increase in the ion temperature at particular geomagnetic latitude continued for about 20 min, and then ceased while the ion velocity was still enhanced. Ion frictional heating lasted until the neutral wind was accelerated to the equivalent level of the surrounded ion flow.