The total, bulk, and grain boundary conductivities of proton-conducting zirconates of general formula AZr_0.95Sc_0.05O_3 – α (AZS), where A = Ca, Sr, Ba, are measured in air with different humidity levels. The conductivity is measured using the four-probe dc method (600–900°C) and impedance spectroscopy (30–800°C). The impact of humid atmosphere on the total, bulk, and grain boundary conductivities of the AZS system is studied at different humidity levels:
= 0.04, 0.61, and 2.5 kPa. Humidity is found to have a considerable effect on the conductivity of our CaZS and BaZS at lower temperatures, suggesting the likelihood of hydronium ion-mediated transport.