The high purity (Ce0.8Ndo.2O1.9)1-x(MoO3)x(x=0,0.005,0.010,0.020; Ce0.8Nd0.2O1.9=NDC) solid solutions were prepared by modified sol-gel method.The structures and electric conductivities were characterized by X-ray diffraction(XRD),field-emission scanning electron microscopy(FESEM) and electrochemical impedance spectroscopy(EIS).The XRD results show that the materials were pure phase with a cubic fluorite structure.Compared to the undoped-NDC samples,MoO3 doped-NDC showed higher sintered density(over 96％) at reduced sintering temperature.The electric conductivity(σt) of (Ce0.8Nd0.2O1.9)1-x(MoO3)x at 400 ℃ was 9.58× 10-4 S/cm when x=0.010,which was higher than that of undoped-NDC samples(σt=3.29× 10-4 S/cm).The obtained optimal amount of the MoO3 was x=0.010 in this system.