Among the most effective proton-conducting oxides for use as electrolytes in fuel and electrolysis cells that are all solid-state are barium cerates. The sol–gel auto-combustion synthesis method synthesised electrolytes of the formula Ba1−xCaxCe0.8Nd0.2O3−δ where x = 0.0, 0.02, 0.04, 0.06, 0.08, and 0.10. XRD, SEM, FTIR, and Raman analysis were done to determine the structure, surface morphology, and bond-stretching vibrations. According to Scherer’s formula, the electrolyte materials’ anticipated crystallite sizes ranged from 20.14 to 36.50 nm. Grain sizes were in the range from 2.5 to 4.5 µm. While FT-IR detected bands related to M–O vibrations, the 362.51 cm−1 vibrational mode related to CeO6 octahedra was identified by Raman spectroscopy. Electrical impedance spectroscopy studies confirmed electrolytes had good ionic behavior, with total conductivities increasing with temperature. The bulk conductivity of the studied perovskite oxides was higher than grain boundary conductivity, with compositions with x = 0.10 exhibiting the maximum overall conductivity.