Thermal decomposition of binary blends composed of poly(trimethylene terephthalate) (PTT) and a phenoxy resin, namely poly(hydroxy ether) of bisphenol A, and prepared by melt blending was studied using thermogravimetric analysis. The thermal decomposition behavior of the blends could be explained in terms of formation and loss of hydrogen bonds and appearance of both low and high molecular weight species due to transesterification reaction between hydroxyl groups of phenoxy with ester bonds of PTT. The kinetics of decomposition reaction was analyzed by Freeman-Carroll, Friedman, Chang, and Vachuska-Voboril methods. It was found that all of the methods well described the decomposition reaction of the blends. The correlation between the calculated values and the chemical nature of the blends was acceptable. Among all the investigated methods the Chang method showed the best correlation with the experimental data. FTIR spectroscopy was employed to study the chemical structure of the blends. The results revealed strong interaction between the blend components in the form of hydrogen bonding. Progress of these interactions was followed with time and temperature. The effects of blending and loss of hydrogen bonding on degradation behavior in this kind of reactive blends were emphasized. (C) 2008 Wiley Periodicals, Inc. J Appl Polym Sci 110: 2924-2931, 2008