The miscibility and thermal degradation of poly(ethylene oxide) (PEO) toughened novolac type phenolic resin were investigated. Differential scanning calorimetry (DSC) results confirmed that phenolic resin/PEO blend was blended completely. Infrared spectra show that hydrogen bonding existed in the blends. Thermal degradation of poly(ethylene oxide) blended with novolac type phenolic resin has been studied utilizing a dynamic thermogravimetric technique in a flowing nitrogen atmosphere at several heating rates (i.e. 5, 10, 20, 40 degreesC/min). Thermal degradation of phenolic resin/PEO blends takes place in multiple steps. Chemical structure and components of blends affected thermal degradation, which coincided with the data from thermal degradation of novolac type phenolic resin/PEO blends by thermogravimetric analysis (TGA).