Herein we report the synthesis of ZIF-67 and ZIF-8 with Dimethyl Sulfoxide (DMSO) as solvent. The structural evolution of ZIF-67 and ZIF-8 as a function of time at room temperature was followed. We have identified the different stages of ZIF-67 and ZIF-8 formation (nucleation, crystallization, growth, and stationary periods) and elucidated its kinetics of transformation. The nucleation and growth of ZIF-67 and ZIF-8 crystals followed Avrami's kinetics. The role that DMSO plays in the crystallization and growth of ZIF-67 and ZIF-8 is discussed. The crystal sizes of ZIF-67 and ZIF-8 in the presence of DMSO as solvent were significantly smaller than those obtained in typical solvents such as methanol, making this solvent appealing for the synthesis of small crystals with relatively narrow size distribution, a property which is highly desirable for diverse functional applications.