The morphological and structural characterization of CeO2 nanocrystallites prepared by forward and reverse precipitation techniques were investigated and compared by powder x-ray diffraction (PXRD), nitrogen adsorption (BET)and high resolution transmission electron microscopy( HRTEM) analysis.The two routes gave quite different materials although in both cases the products were essentially highly dense particulates. It was found that the reverse precipitation technique gave the smallest crystallites with the narrowest size dispersion.Thisr route also gave as-synthesized materials with higher surface areas. HRTEM confirmed the observations made from PXRD data and showed the two methods resulted in quite different morphologies and surface chemistries. The forward route gives products with significantly greater densities ofáCe 3■ species compared to the reverseároute. Data are explained using known precipitation chemistry and kinetic effects.