We demonstrated the in situ synthesis of CdOx and ZnOx and their direct deposition on the multiwalled carbon nanotubes (MWCNTs) through an ionic liquid-assisted sonochemical method (IIASM). The morphologies of CdOx and ZnOx such as nanoparticles and layers were determined by the types of ionic liquids (ILs). When MWCNTs were functionalized by less polar and more viscous ILs such as BMimPF(6) and HMimBF(4) compared to BMimBF(4), the layered structures or aggregation of CdOx and ZnOx were constructed. For the presence of BMimBF(4), the discrete CdOx and ZnOx nanoparticles were formed due to the fast growth into nanocrystals by the high mobility of precursors. Furthermore, nanoparticles were not uniformly coated and aggregated in polar BMimHSO(4) and high concentration of IL Therefore, the morphologies of the decorated nanoparticles could be controlled by the properties of ILs as the mobility of precursors for particle growth was strongly influenced by the surface chemistry of MWCNTs. (C) 2012 Elsevier B.V. All rights reserved.