In this paper, we discuss two mechanisms of preparation of composite nanoparticles in liquid dispersions and their effects on size distributions of nanoparticles. In the first case of an adsorption process, the added particles form an external layer of approximately equal thickness on the surface of each of the supporting particles. The radii of all the particles then grow by the same amount irrespective of their original size. In the second case, analogous to bulking, secondary nanoparticles also settle over the dominant surfaces of internal micro-pores inside the primary particles, and sizes of the resulting composite particles then increase by the same factor. As each of these mechanisms affects the size distribution of nanoparticles in a different way, even a simple comparison of the initial and the final distribution functions can indicate the nature of the modification process. (C) 2013 Elsevier Ltd. All rights reserved.