Condensation and evaporation of a low temperature nano-sized argon particle moving in a gas/vapor environment were analyzed using the molecular dynamics simulation. First evaporation temperature for various heating rates was found and successfully compared with the analytic result. Condensation and evaporation rates observed through simulation depended on particle velocity and thermodynamic properties of the gas, and the radial distribution of particle temperature was found to be a good indicator to characterize the process. Characteristics of condensation and evaporation for four different particle velocities and various environmental conditions were discussed in detail. In low gas density environments all the gas atoms got condensed on the particle, and in high gas density environment condensation/evaporation characteristics became much different depending on particle velocity. (c) 2007 Elsevier Ltd. All rights reserved.