Barium zirconate ceramics doped with Y and Yb, BaM(x)Zr(1-x)O(3-alpha) (M = Yb, Y), are perovskite single phases and exhibit protonic conduction in moist nitrogen atmospheres at temperatures 500 < T (degrees C)< 1000. Samples with x = 0.10 have been investigated by ac and de electrochemical techniques. Conductivities with Yb as dopant were larger, by a factor approximate to 10, than those with Y as dopant. Conductivities for Yb-doped samples (e.g. sigma(b) (750 degrees C) approximate to 2 x 10(-4) S cm(-1)) are lower than those reported for analogous cerates. Throughout the experimental temperature range, the apparent conductivity found in de studies (summing resistances due to the electrolyte and electrode-electrolyte interfacial phenomena) was lower, by a temperature independent factor approximate to 2, than the conductivity determined by ac techniques.