TG-FTIR measurements of polyurethanes derived from mono- and disaccharides and their raw materials were carried out in order to investigate the thermal decomposition mechanism. It was found that polyurethanes decomposed in two steps; the first step of decomposition was observed at about 300 to 450 degrees C and the second at about 450 t0 to 700 degrees C. The first step was attributed to the breakage of pyranose rings, aromatic rings and/or alkylene chains and the second step to the production of CO2, and H2O.