The region of preferred crystal nucleation of the two known polymorphs of L-glutamic acid (C(5)H(9)NO(4)), the metastable alpha and stable beta, from pure aqueous solution has been recognized by following a swift cooling crystallization process in the temperature range 1-40 degrees C. Aqueous solution prepared for a selected saturation was taken to 80 degrees C and cooled down to various temperatures in the range 1-40 degrees C in steps of every 1 degrees C abruptly with constant stirring. The observed nucleation and grown micro-crystallites in the solution were examined under optical microscope and their morphologies and polymorphic forms were evaluated. Results obtained from this investigation at all the 40 experimental temperatures elucidated a clear distinction of the preferred nucleation regions of alpha, beta and combinations of alpha and beta in the solution in the above mentioned temperature range and the results are repeatable. Form of crystallization was confirmed by Powder X-ray Diffraction (PXRD). Further the grown polymorphs were characterized by Differential Scanning Calorimetry (DSC), optical transmittance and Second Harmonic Generation (SHG) studies. (C) 2010 Elsevier B.V. All rights reserved.