The melting and nucleation of the iron nanoparticles were investigated by molecular dynamics simulation. The nanoparticle of the bcc single-crystal was uniformly melted from the surface at a melting point during heating, whereas a nucleus was generated near one side of an undercooled liquid droplet and the solidification spread toward another side at a lower temperature during cooling. The melting point and nucleation temperature decreased with particle radius. Moreover, the solid-liquid interfacial energy was estimated to be 0.101 J/m(2) using a Gibbs-Thomson equation, which is of the same order as the experimental value based on Turnbull-Fisher's classical nucleation theory. (C) 2007 Elsevier B.V. All rights reserved.