An emerging nanofabrication technology is to synthesize nanoscale inorganic materials with narrow size distribution using biological systems, which are size-constrained, fairly robust, and easily removable. Apoferritin, a spherical and hollow protein complex, was subjected to atomic layer deposition of TiO(2). The growth of TiO(2) on the protein surface was investigated as a function of the precursor exposure and purge length. Thermal pretreatment and osmotic dehydration lead to controllable deposition both on the outer surface and within the inner cavity of apoferritin. Depending on the experimental conditions, either hollow spherical nanoparticles or core-shell nanoparticles comprising TiO(2) were identified.