An interesting morphological evolution process driven by a competition between the thermodynamic and kinetic factors is first experimentally observed in a replacement reaction. At relatively short reaction time, a kinetic factor driven by concentration gradient dominates the growth process and contributes to the formation of silver dendrite due to a non-equilibrium and anisotropic growth. While at longer reaction time, the small grains may have sufficient time to relax and transfer to the minimum energy position thus obtain a thermodynamically stable hexagonal plate-like silver nanostructures. The observation here provides a theoretical study system for a better understanding of the microscopic origin and morphological transition. (C) 2007 Published by Elsevier B.V.