The electronic level of interstitial Cr in silicon according to the transition Cr0i→Cr+i(3d6→3d5) was determined by correlating the electron paramagnetic resonance (EPR) signal of Cr+to Hall measurements on identical samples. The procedure gives the donor level located atEc−0.222±0.005 eV. From the experiments may be inferred that there is no Cr++istate aboveEv+0.05 eV. The solubility of interstitial Cr in silicon is retrograde at 1300° and has a maximum value of 5×1015cm−3.