Degradation behavior of the electrical resistance of acceptor (Mg)-doped BaTiO3 ceramics was contrasted against different acceptor concentrations. Coarse-grained specimens with uniform grain sizes and different acceptor concentrations were prepared by sintering both in air and a reducing atmosphere. The specimens sintered under both atmospheres showed similar trends in the degradation behavior with a critical dependence on the acceptor concentration. The time to degradation decreased systematically with the increase of acceptor concentration. An impedance spectroscopy study was conducted on these samples at various temperatures. An equivalent circuit analysis of these data was considered, from which bulk and grain-boundary conductivity was determined for each composition as a function of grain size. Attempts were made also to determine the ionic conductivity for the different samples as a function of temperature and doping concentration.