[en] The electrical conductivities of translucent BaZr_0_._5Ce_0_._3Y_0_._2O_3_-_δ (x = 0.5, BZCY532), BaZr_0_._6Ce_0_._2Y_0_._2O_3_-_δ (x = 0.6, BZCY622) and BaZr_0_._7Ce_0_._1Y_0_._2O_3_-_δ (x = 0.7, BZCY712) proton conductors were investigated systematically in different atmospheres and also at different oxygen partial pressures. The obtained results indicate that translucent BZCY532, BZCY622 and BZCY712 ceramics are pure oxygen-ion and proton conductors without unfavorable electronic conduction. In addition, they represent promising proton conductors to be used as intermediate temperature solid oxide fuel cell electrolytes.