Comparative analysis of the yield-stress temperature dependences for polycomponent and binary solid solutions with a b.c.c. lattice (AlCrFeCoNi, AlTiVCrNbMo, Ti$_{25}$Zr$_{25}$Hf$_{25}$Nb$_{12.5}$Ta$_{12.5}$, VNbMoTaW, Fe–Cr, Fe–Mo, Fe–W, Cr–Fe), and some pure b.c.c. metals is carried out. Using the thermoactivation analysis, the values of the activation energy of dislocation movement and the activation volume are calculated. As shown, for the binary and polycomponent solid solutions, an increase in athermal component of a flow stress is characteristic in comparison with pure b.c.c. metals. In this case, in comparison with pure metals, multicomponent solid solutions demonstrate an increasing of the thermal component, while for binary b.c.c. alloys, there is a weakening of the temperature dependence of a flow stress. The nature of this effect is discussed. As shown, high athermal solid-solution hardening of polycomponent solid solutions can be associated with a change of the Burgers vector (by both the length and the direction) along the dislocation line and an appearance of a component perpendicular to the glide plane. The observed increase of the flow-stress thermal component in polycomponent b.c.c. solid solutions is presumably due to the presence of a high concentration of points of fixation of the thermally activated dislocation segment by atoms of elements, which have a high level of size-elastic discrepancy in comparison with an average value for the alloy.