The composites based on the oxygen-ion and proton conductor Ba2In1.7W0.3O5.45 with a 30 mol % Ba2InNbO6 addition were studied. The processing of the compact samples of the composite electrolyte at 1430°C gave ceramics with a density of 95%. The total electric conductivity of the composite in dry and humid atmospheres decreases by ~0.5 order of magnitude compared with the conductivity of the matrix.