In this paper, we report our systematic study on solution crystallization of an industrially important compound, L-glutamic acid, in an oscillatory baffled crystallizer (OBC). The effects of linear cooling rates and solution concentrations on metastable zone width (MSZW), nucleation parameters, and crystal polymorphism are investigated. The MSZW increases with an increase in the cooling rate, while it remains more or less unchanged for different solution concentrations. The metastable 8 crystals are favored for low to medium solution concentrations for all cooling rates, while ß crystals are favored for relatively high solution concentrations. The OBC offers more uniform mixing and better heat transfer environment than traditional stirred tank vessels (STC), resulting in a higher crystallization temperature, suggesting that the OBC would be more effective in promoting nucleation, thus presenting a narrower MSZW during a cooling process than traditional STC. © 2008 American Chemical Society.