Using nanoparticles of CeO2 and ZrO2 prepared by the chemical precipitation method as starting materials, the single-phase cubic Ce0.5Zr0.5O2 solid solution (c-Ce0.5Z0.5O2) has been synthesized under 3.1 GPa at 1073 K for the first time. The structure of the c-Ce0.5Zr0.5O2 has not been changed before and after annealing at 773 K for 1 h. Only an unknown EPR signal (g =1.990) has been observed in the c-Ce0.5Zr0.5O2 and not varied after annealing at 773 K for 1 h, which exhibited that there exists no Ce3+ in the c-Ce0.5Zr0.5O2 and the Ce4+ has not been reduced into Ce3+ after annealing. The transport mechanism is ionic for the c-Ce0.5Zr0.5O2. The bulk conductivity (a =1.2×10-5 S/cm at 823 K, σ=2.1 ×10-3 S/cm at 1123 K) is the same as that of CeO2, but smaller than that of Y2O3-stabilized ZrO2. A marked curvature at T = 823 K has been observed in the Arrhenius plot of the bulk conductivity. The activation energy below 823 K is lower than that above 823 K, and the reason has been discussed. Using nanoparticles of CeO2 and ZrO2 prepared by the chemical precipitation method as starting materials, the single-phase cubic Ce0.5Zr0.5O2 solid solution (c-Ce0.5Z0.5O2) has been synthesized under 3.1 GPa at 1073 K for the first time . The structure of the c-Ce0.5Zr0.5O2 has not been changed before and after annealing at 773 K for 1 h. Only an unknown EPR signal (g = 1.990) has been observed in the c-Ce0.5Zr0.5O2 and not varied after annealing at 773 K for 1 h, which exhibits that there exists no Ce3 + in c-Ce0.5Zr0.5O2 and the Ce4 + has not been reduced into Ce3 + after annealing. The transport mechanism is ionic for the c-Ce0. 5Zr0.5O2. The bulk conductivity (a = 1.2 × 10 -5 S / cm at 823 K, σ = 2.1 × 10 -3 S / cm at 1123 K) is the same as that of CeO 2, but smaller than that of Y 2 O 3 The marked energy at T = 823 K has been observed in the Arrhenius plot of the bulk conductivity. The activation energy below 823 K is lower than that above 823 K, and the reason has been discus sed.