The electrical conductivity of SrBi4Ti4O15 (SBT) has been measured under controlled oxygen partial pressure. Both acceptor and donor doping effects were studied using de conductivity and impedance measurements. In addition to the ceramic samples with random grain orientation, grain oriented samples were prepared by hot forging. It has been shown that the conductivity of SBT is electronic p type in air at low temperature and it is n type at high temperature (greater than or equal to 700 degrees) up to 1 atm pO(2). The conductivity is increased by Mn doping and decreased by Nb doping at low temperatures (less than or equal to 220 degrees C) and decreased by Mn coping and increased by Nb doping at high temperatures (700-1000 degrees C). The slope of the conductivity versus pO(2) curve is significantly decreased by Mn coping above 700 degrees C in the pO(2) range from 1 atm to 10(-5) atm. (C) 1999 Elsevier Science Limited. All rights reserved.