The gadolinium-doped ceria is investigated as electrolyte materials for intermediate temperature solid oxide fuel cells (IT-SOFCs) due to its oxide ion conductivity. The doping of Gd3+ to Ce4+ can introduce a small strain in the lattice thereby improved conductivity with low activation energy is expected. The 20 mol. % gadolinium doped ceria (Ce0.8Gd0.2O2−δ) nanocrystalline powder is prepared here by citrate - complexation method. The XRD, Rietveld refinement, FTIR, UV-Visible, FESEM/EDX, and a c - impedance techniques are used to characterize this sample. The oxide ion conductivity is determined between 523 − 1023 K. The Ce0.8Gd0.2O2−δ shows highest oxide ion conductivity of 6.79 × 10−3 S cm−1 and 1.11 × 10−2 S cm−1 at 973 K and 1023 K, respectively. The Ce0.8Gd0.2O2−δ showed lower activation energies of 1.09, 0.70, and 0.88 eV for grain, grain boundary, and total conduction, respectively. Thus, the nano crystalline Ce0.8Gd0.2O2−δ is proposed as potential electrolyte for IT-SOFCs.