Si:H nanoparticles have been generated from 3 nm to 500 nm in count mean diameter (CMD) using a plasma chemical vapor deposition (CVD) system. In the present work, the nanoparticles are synthesized using cold plasma in order to get monodispersed size distribution with a combination of square wave modulated RF pulse plasma and a hydrogen gas pulse for better control of their size. The size of synthesized nanopartides was measured by scanning mobility particle sizer (SMPS). The synthesis was carried out using pulse plasma with on-time of 1 s and off-time of 4 s. During 1 s on-time of plasma we added hydrogen gas pulses varying from 0.1 s to 0.9 s. Our results show that by utilizing dual pulse plasma and by controlling hydrogen gas pulse on-time we achieved smaller diameter Si nanoparticles. Hence, it is easier to generate smaller nanoparticles which generally have quantum effect and be utilized for various applications especially in solar cell application. (C) 2011 Elsevier B.V. All rights reserved.