Two-step sintering with controlled oxygen partial pressure by using metallic buffer was applied to obtain dense non-stoichiometric CeO_2-x. The samples prepared with single step sintering were cracked. The two-step sintering promoted almost full densification ≈ 98% in relative density without any cracks. Relative density of CeO_2-x reached more than 98% of the theoretical density. The value of x in CeO_2-x was obtained in the range of 1.68 in Mn/MnO to 1.98 in Co/CoO.