Thermally activated deformation mechanisms in three different W-Re alloys were investigated by performing high temperature nanoindentation experiments up to 800 °C. With increasing Re content the athermal hardness increases, while the temperature-dependent thermal contribution is strongly decreased. This results in a reduced strain rate sensitivity for W-Re alloys compared to pure W. The origin of this effect is a reduction of the Peierls potential due to Re, manifesting in an increased activation volume at lower temperatures. This gives rise to a solid solution softening effect, while at high-temperature application the mechanical behavior is governed by dislocation-dislocation interaction and solution strengthening.