The inventive method for forming articles from foaming polymers and compositions based thereon consists in forming articles using a heat energy released by water exposed to the action of microwave radiation al n temperature equal to or less than 170° C., wherein said temperature is attained, controlled and limited by adjusting a vapor pressure in a forming chamber. The inventive device for carrying out said method comprises a forming chamber, which is made of a microwave transparent material, filled with the mixture of prefoamed or granulated foaming polymer or a composition based thereon with water and is placed in a microwave radiation producing channel, and a unit for equalizing a pressure in said forming chamber. The forming chamber and the body thereof made of a microwave non-transparent material are provided with air holes, which are also used for connecting the forming chamber to the pressure equalizing unit.