High electrical conductivity is one of the main obstacles for advances of bulk BiFeO3 ceramics in piezoelectric applications. Here, we demonstrate that the electrical conductivity of BiFeO3 can be lowered by compositional modification with Bi0.5K0.5TiO3 and further reduced by annealing in oxidizing or reducing atmospheres. These manipulations also allow for tailoring of other functional properties. In particular, we demonstrate that the electric field induced strain performance of bulk bismuth ferrite can be significantly improved by addition of 30% Bi0.5K0.5TiO3 and thermal annealing in an inert atmosphere. ; (c) 2014 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4869976]