Herein we report the structural evolution of ZIF-67 as a function of time at room temperature. We have identified the different stages of ZIF-67 formation (nucleation, crystallization, growth, and steady state periods) and elucidated its kinetics of transformation. It was found that the nucleation and growth of ZIF-67 crystals followed the classic Avrami's kinetics. Fundamental studies on the kinetics of formation of porous crystals demonstrated here should facilitate the preparation of MOF phases with controlled crystal size and extent of crystallinity. (C) 2015 Elsevier B.V. All rights reserved.