The purpose of this study was to increase the thermooxidative stability and flow of high-molecular polyoxyethylene (HMPOE) by introducing readily available, technologically convenient, and economical additives. Binary systems consisting of HMPOE with mean viscosity molar mass (M) over bar(upsilon) = 3,2.10(6) g.mol(-1) and inorganic salts from both the seawater and sea lye and, also, MgCl2 of concentration from 1 to 10 mass % with respect to HMPOE, were prepared. The thermal behavior of these systems was studied by using dynamic thermal analysis, dynamic viscometry, and melt index determination. The presence of salts of concentrations from 3 up to 10 mass % in HMPOE was found to increase the temperatures of initial thermooxidative decomposition of the polymer. At the same time, the degree of viscosity reduction (-Delta eta, %) corresponding to lowering the average molar mass after the heat treatment for 20 h at 150 degrees C decreased. Another effect of the salts was found to be the increased melt flow of HMPOE above 250 degrees C. The best stabilizing effect was obtained in the presence of salts in sea lye and, also, MgCl2.