Abstract The magnetoimpedance effect is employed in the analysis of the thermal dependence of the magnetic properties in soft magnetic nanocrystalline Fe 66.5 Cr 7 Si 13.5 B 9 CuNb 3 alloy. The characteristic magnetic transition associated with the magnetic decoupling of the ferromagnetic crystallites around the Curie point of the residual amorphous phase (≈160 K) has associated maximum values in both impedance components. Their temperature and field dependence reflect the characteristic temperature evolution of the basic magnetic parameters in these nanocrystalline systems.