Nanocrystalline triple-doped ceria based solid electrolyte materials (CuxMn0.1-xZr0.1Ce0.8O2, where x = 0, 0.02, 0.04, 0.06, 0.08 and 0.1, as well as Cu0.08Mn0.02ZryCe0.9-yO2, where y = 0 and 0.1) for intermediate temperature solid oxide fuel cells were successfully synthesized by co-precipitation method with sonication and sintered at 1150 °C for 4 h in air. Relative densities of all the samples were above 90–96%. All systems were characterized by XRD, SEM-EDS and TG-DSC-MS for the investigation of structure and microstructure with elemental composition. The electrical conductivity of these materials was measured by AC impedance spectroscopy in the temperature range of 500–750 °C in air. It was shown that Cu0.08Mn0.02Zr0.1Ce0.8O2 ceramics possessed the maximum conductivity of 8 · 10−3 S/cm at 600 °C in air.