The results of the study on the reactions of melamine cyanurate with ethylene carbonate were presented. As a result of the reactions, polyetherols containing thermostabile 1,3,5-triazine and perhyroxo-1,3,5-triazine rings in their structure were obtained. Basic physical properties such as density, viscosity, hydroxyl number, weight changes were measured. The polyetherols were applied as a polyol component to receiving of thermoresistant polyurethane foams. Some of the properties of the obtained foams were investigated. The value of the apparent density is between 51 and 71 kg/m3, compressive strength 222-356 kPa and the content of the open pores between 14-33%. Thermal resistance was also studied by means of the TGA method. It was found that oxygen index of the selected compositions is between 20-22%.