Two metastable polymorphs of paracetamol (forms 11 and 111) were prepared by appropriate thermal methods from binary mixtures containing 10% (w/w) of hydroxypropylmethylcellulose. By controlling the reheating step, it was possible to address the recrystallization of the drug either into form 11 or III. Moreover, it was observed that form 111 transforms either into form 11 or I depending on the preparation method. The physical characterization of the polymorphs was performed by means of micro-Fourier transform infrared spectroscopy (MFTIR) and powder X-ray diffractometry (PXRD), both temperature controlled. (C) 2003 Elsevier Science B.V. All rights reserved.