Since plasma is regarded as one of the multifunctional fluids which has high energy density, chemical reactivity, controllability by an external electromagnetic field and variable transport properties such as electrical conductivity, it is considerably effective for the synthesis of nano-particles. Since a radio frequency inductively coupled plasma (RF-ICP) has several advantages, the synthesis of ultrafine powders of metals and ceramics with high purity can be easily achieved by the steep temperature gradients at the tail. In the present study, it is clarified how the number density, diameter and specific surface of the produced nano metal-particles of At, Ti, Au and Pt are influenced by the operating conditions such as the quenching gas flow rate and the powder feed rate of the RF-ICP reactor by numerical investigation. For all the metals, the increase in the quenching gas flow rate results in the increase in the particle number density, the decrease in the mean diameter and the increase in the specific surface. The increase in the powder feed rate causes the increase in the mean diameter but the decrease in the specific surface. The results of four metals are markedly different from each other due to their own material properties of saturation pressure and surface tension. (C) 2003 Elsevier B.V. All rights reserved.