The effect of doping potassium on the A-site of BaZrO3 for application as a high temperature proton conductor was investigated. The synthesis of K-doped BaZrO3 and its characterization by XRD, SEM and EDX is described. Four-probe dc conductivity was measured on dense and porous (44% porosity) samples in varying partial pressures of oxygen, , and water vapor pressure, , over a temperature range from 500 to 700oC. The dependence of total conductivity in a dry atmosphere on oxygen partial pressure could be described by the equation . The experimental data were fitted to this equation with good accuracy, from which the electron-hole and oxygen-ion conductivities were determined. The activation energies for oxygen-ion and electron-hole conduction were estimated to be 0.85 and 1.14 eV, respectively. A significant increase in total ionic conductivity was observed in humid atmospheres, which is attributed to high protonic contribution.