We have determined the valence band discontinuity ΔEv of strained Si1−xGex on unstrained (100) Si using temperature‐dependent current–voltage characteristics (I–V‐T) of Si/Si0.83Ge0.17/Si heterostructures. In a first step, the measurements were performed on a Schottky diode, and in a second step, on a sample with ohmic contacts. The values of ΔEv obtained by these two different procedures are comparable. Moreover, they are in good agreement with the theoretical value of ΔEv=0.84x=143 meV predicted by Van de Walle measurements.