Ceria and ceria based compounds are a key materials in several energy related technologies. As cerium oxide (e.g. in acceptor doped CeO_2-δ), the material presents distinctive mechano-chemo-electrical properties related to high oxygen defect concentration, fast defect mobility and large chemical expansion.  In this work we show that cations diffusion and net fast mass diffusion mechanisms can be triggered at relatively low temperatures (T > 800 °C) under low oxygen partial pressure (pO₂ < 10^-12 atm) conditions. Such effects are promoted by coupling high content of oxygen defects and cation size changes from Ce⁴⁺ to Ce³⁺, activating fast densification, low viscosity mass flow, and unexpected microstructural evolution of the compound. On the other hand, in composites and at soli-solid interfaces with other metal oxides, ceria leads fast chemical transformations and phase changes. A detailed analysis of these phenomena indicated that tuned chemo-thermal conditions can be designed in treatments at controlled pO₂ conditions and temperatures, resulting in novel ceria-based compounds and enhanced electrochemical properties.