The textural and structural properties of high specific surface area (HS) Ce_xZr_1-xO₂ mixed oxides (CeZrMO) and their modification upon thermal aging have been investigated. Results from BET area determination and complete porosity analysis, as well as high-resolution electron microscopy, XRD, Raman and FTIR spectroscopies are presented. Some relationships between the molar composition of the binary systems and their textural and structural properties are presented. In addition, it has been possible to propose an explanation for structural features of the mixed oxides (solid-solution structures and possible phase segregation) as a function of Ce content, a point of great interest for the knowledge of phase composition and stability of CeZrMO.