The electrical properties of donor (La3+) doped BaTiO3 samples with a donor concentration in the range from 0.3 to 1.5 mol.% of La were studied. Samples were sintered at a low partial pressure of oxygen in order to facilitate anomalous grain growth and donor incorporation. In order to optimise the PTCR anomaly, the samples were annealed in air at 1100 degrees C. Results show that with the use of a specific sintering profile PTCR ceramics containing an amount of donor dopant > 0.3 mol.%, can be prepared. Heavily doped samples which do not exhibit anomalous grain growth show a core shell structure.