This study was designed to investigate the thermal characteristics of Hydroxypropyl Methyl Cellulose (HPMC). Because HPMC is used in various industries extensively, it is very important to clarify the thermal characteristics in terms of its potential hazards and the spontaneous. In this study, we performed thermal analysis with the TG-DTA and Spontaneous Ignition Tester (SIT). Based on the data of the SIT, we know that the critical spontaneous ignition temperature and the apparent activation energy of HPMC were about 185 degrees C and 104.54 kJ/mol respectively. However, when the amount of sample is larger to a certain degree, ignition can occur below this temperature. At a thickness of I m sample of infinity flat was calculated to have a critical temperature value of approximately 180 degrees C by Frank-Kamenetskii's method. Upon analyzing thermal behavior using the TG-DTA, we found that the pyrolysis transpired at 200 degrees C, below the rate of temperature of 1 K/min, which is slightly lower than that of common cellulose. Regarding gas analysis, carbon monoxide (CO) was emitted at the start of the reaction. (C) 2008 Published by Elsevier Ltd.