The electrical conductivity of single crystals of Cr2O3has been measured as a function of temperature from 600° to 1400°C and as a function of oxygen partial pressure from 1 to 10−6atm. The results show a high‐temperature ``intrinsic'' conductivity that is independent of oxygen pressure, and a low‐temperature defect‐controlled conductivity that varies with oxygen pressure in a manner which cannot be determined from measurements on single crystals. The very low mobility deduced from the intrinsic conductivity suggests an interpretation in terms of the theory of small polarons. Although the possibility of charge transport in very narrow bands cannot be ruled out on the strength of the experimental data, it seems less likely. The model suggested is that of charge formation and transport in localized 3dlevels of the cations.