The electrical conductivity and oxygen content in SrFe1-xMoxO3-delta, where x = 0.05, 0.1 and 0.2, are studied at 650-950 degrees C within a wide range of oxygen partial pressure. The partial contributions of ion and electron charge carriers are obtained from the conductivity analysis. At relatively small level, x similar to 0.05, the molybdenum dopant favors enhanced oxygen-ion contribution. Further increase in the dopant content results in deterioration of the oxygen-ion component of conductivity. At the same time, considerable increase of the n-type electron component is observed at x > 0.05, which is explained by the involvement of Mo5+ cations in electron transport. The mobility of n-type electron carriers is found to increase with molybdenum content while the mobility of p-type electron carriers tends to decrease. (c) 2008 Elsevier B.V. All rights reserved.