Highly crystalline ceria nanoparticles in porous carbon matrixes are formed by the simple pyrolysis of cerium loaded ion-exchange resins. The resulting cerium/carbon composite structures maintain the original bead or powder form of the precursor resins with an increase in specific surface area. Incorporating Gd or Pr dopants with Ce in the resins provide uniform dispersions and equally small ceria crystallites upon pyrolysis, typically 1–2 nm. Highly active particles are obtained, as demonstrated by air light-off of the ceria/carbon composites as low as 200 °C. The combination of the high pyrolysis temperature (1000 °C) and the controlled dispersion and stable environment provided by the ion-exchange resin precursors are key to provide highly crystalline and extremely small ceria particles in a conductive carbon matrix. Various types of cation-exchange resins are considered and the best results are obtained with highly cross-linked or styrene-divinyl benzene (DVB) matrixes and cation chelating or weak acid functionalities.