Barium cerates (BaCe_(1-x)M_xO_(3-#alpha#) with M=Gd, Eu and x=0.15) were prepared and studied with x-ray diffraction, impedance spectroscopy, and their hydrogen permeation flux determined by mass spectrometry. BaCe_(0.85)Gd_(0.15)O_(3-#alpha# (BCGO) and BaCe_(0.85)Eu_(0.15)O_(3-#alpha#) (BCEO) demonstrated a negligible difference in conductivity between moist air and moist forming gas atmospheres below 450 deg C, but the conductivity difference gradually increased between 450 deg-750 deg C with the conductivity higher in moist air. BCEO exhibited a higher conductivity than BCGO in the moist forming gas atmospheres. BCEO demonstrated a dramatic increase in hydrogen flux compared to BCGO (0.42 cm~3/(cm~2-min) versus 0.05 cm~3/(cm~2-min) at 600 deg C). This increased hydrogen flux indicates that BCEO has an electronic conductivity component in low Po_2 atmospheres.
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