The monodispersed hybrid silica particles could be synthesized through the one-step sol-gel reaction with organosilane (3-mercaptopropyl trimethoxysilane, MPTMS) in aqueous solution. In this study, the effects of the concentrations of organosilane and the catalyst ((NH(4)OH) on the formation of silica particles were investigated. For the first time we reported the successful one-step synthesis of monodisperse hybrid silica particles using organosilane chemicals in the previous study. In order to obtain better insight about the reaction processes, the silica particles were prepared in the presence of various concentrations of MPTMS and NH(4)OH. On the basis of the experimental results, it was found that particle size increases as the concentration of organosilane increases. Also, as the concentration of catalyst increases, the diameter of these monodisperse particles decreases significantly. This research can contribute to a new broad avenue for the surface functionalization and hybrid material formation with various sizes. (C) 2011 Elsevier Ltd. All rights reserved.