Aerosol nanoparticles draw great attention due to their unique physico-chemical properties that can be harnessed for innovative applications as well as for their potential impact on public health and the environment. Microscopic characterization of these particles is critically important to understand the unique particle properties and their interaction with biological systems. Here we report on a simple and efficient method for size, morphology, and crystallinity analyses of aerosol nanoparticles through transmission electron microscopy (TEM). The method uses carbon nanotubes (CNTs) as the particle support on conventional TEM grids. The CNT support significantly improves the quality of high resolution TEM (HRTEM) imaging due to the unique properties of CNTs, the high probability of particles sitting at the edge of CNTs, and the minimization of the interference interaction between the electron beam and the supporting substrate. The improved HRTEM images are useful for detailed characterization of nanoparticles, and particularly suitable for analyzing core-shell nanoparticles. (C) 2008 Elsevier Ltd. All rights reserved.