<p>This study systematically investigated the effect of CeO₂ addition on the oxidation roasting and subsequent hydrogen reduction behavior of Bayan Obo pellets. A combination of FactSage thermodynamic calculation, isothermal reduction experiments, XRD, and SEM–EDS analysis was employed to evaluate the influence of CeO₂ on the compressive strength, reduction degree, swelling index, microstructure, and elemental distribution of the pellets. Thermodynamic calculations indicated that CeO₂ remained chemically inert and did not react with the iron-containing or slag phases during both oxidation and reduction processes. The compressive strength of the pellets was significantly influenced by the CeO₂ content, initially increasing from 3016 N/P to 3534 N/P at 0.5 wt% CeO₂, and then decreasing to 2785 N/P at 2.0 wt% addition. At lower reduction temperatures of 600 ℃ and 700 ℃, the incorporation of CeO₂ notably decreased the reduction degree from 44.54 to 33.36% and from 74.05 to 63.68%, respectively. In contrast, at higher temperatures (800 ~ 1000 ℃), CeO₂ had no significant impact on the reduction degree. A critical finding was that CeO₂ addition effectively suppressed reduction swelling, with a pronounced inhibitory effect observed at content between 0.5 wt% and 1.5 wt%. At 1000 ℃, the swelling rate was markedly reduced from 65.05 to 38.12%. However, excessive CeO₂ addition (&gt; 1.5 wt%) disrupted the hematite crystal structure, consequently diminishing pellet strength and the anti-swelling effect.</p> Graphical abstract <p></p>