The morphology of ultrafine LiCoO2 powders prepared by a sol-gel process was examined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The purity and grain size of LiCoO2 powders was dependent upon the pH value of the sol-gel process. The grain sizes measured by tapping mode AFM were 68, 74 and 100 nm, for samples made in acidic, neutral and basic media, respectively. Compared with grains synthesized using a solid-state high temperature method, which ranged from 5 to 20 mu m, the grains synthesized using a low-temperature sol-gel process were at least 70 times smaller. Only products with small grains made in acidic media displayed a pure LiCoO2 XRD pattern, implying that growth kinetics were favored in non-acidic media. (C) 1997 Elsevier Science S.A.