In this study, we aimed to examine the effect of dopant type and concentration on the ionic conductivity of ceria-based electrolytes. Ceria electrolytes doped with samarium (SDC), gadolinium (GDC), neodymium (NDC), and lanthanum (LDC) for solid oxide fuel cells were prepared through the polyol process. Acetate compounds of cerium and dopants were used as starting materials, and triethylene glycol was used as a solvent. Prepared powders and pellets were characterized by TG/DTA, XRD, FTIR, SEM, EIS, and EDS techniques. The results of the TG/DTA and XRD indicated that a single-phase fluorite structure formed at the relatively low calcination temperature of 500 degrees C. The relative densities of the pellets were higher than 90% and these finding were supported by the SEM images. The lattice parameters of the samples increased with the dopant concentration. According to the electrochemical analysis results, the samples with maximum conductivity values were SDC-20, GDC-15, NDC-15, and LDC-15. The results of the impedance spectroscopy revealed that the SDC-20 sample exhibited the highest ionic conductivity with a value of 4.29x10(-2)S/cm at 800 degrees C in air.