Single phase solid solution Ce 1− x Bi x O 2− δ with the composition of x=0.1–0.5 were successfully synthesized at room temperature using simple and fast Self Propagating Room Temperature procedure (SPRT). Thermal stability of these solid solutions with different concentration of Bi cation was investigated at various temperatures up to 1400°C by applying thermogravimetric analysis (DTA/DTG/TG). Powders were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and Infra Red spectroscopy (IR). It was revealed that all samples with concentration of bismuth higher than 10at.% are unstable during thermal treatment, resulting in Bi leaving the structure of ceria and formation of β-Bi 2 O 3 as second phase. Moreover, at a certain temperatures bismuth begins to evaporate.