We present a novel technique for controlling oxygen fugacity, which is broadly used to in-situ measure the electrical conductivities in minerals and rocks during diamond anvil cell experiments. The electrical conductivities of olivine aredetermined under controlled oxygen fugacity conditions (Mo-MoO2) at pressures up to 4.0 GPa and temperatures up to 873 K. The advantages of this new technique enable the measuring of the activation enthalpy, activation energy, and activation bulk volume in the Arrhenius relationship. This provides an improved understanding of the mechanism of conduction in olivine. Electrical conduction in olivine is best explained by small polaron movement, given the oxygen fugacity-dependent variations in conductivity.