The role of ceria doping (0.75 - 3 mol%) on solid-solid interactions between ferric and cobaltic oxides was investigated. The investigated solids were characterized by TGA, DTA, XRD and HRTEM. The results revealed that ceria much enhanced the formation of nanosized CoFe₂O₄ (10 - 30 nm). The stimulation effect of ceria towards cobalt ferrite formation was evidenced from analysis of DTA and XRD investigations. In fact, the area of endothermic peak located at 575℃- 680℃ relative to solid-solid interaction between ferric and cobaltic oxide increased by increasing the dopant concentration. This treatment decreased the activation energy of formation of the produced ferrite from 33 - 9.2 kJ/mol upon doping with 3 mol% CeO₂. HRTEM analysis revealed the formation of homogenous nanosized CoFe₂O₄. The formation effect of ceria dopant towards the formation of CoFe₂O₄ has been tentatively attributed to an effective increase in the mobility of the reacting cations.