The thermal decomposition behavior of the miscible cellulosic blends cellulose( Cell)/poly(N-vinyl-2-pyrrolidone) (PVP), Cell/poly( ethylene glycol) (PEG), and Cell/poly(vinyl alcohol) (PVA) was investigated by thermogravimetry. The thermal stability of Cell in the Cell/PVP blends decreased but that of Cell in the Cell/PEG and Cell/PVA blends was hardly influenced. The thermal stability of synthetic polymers in the blends was little affected. The difference in thermal decomposition behavior was correlated to the difference in miscibility.