PURPOSE: To obtain a heat-stable molding suited for use as a friction lining of a brake lining or the like.

CONSTITUTION: There is provided a process for producing a heat-sable molding which comprises molding and vulcanizing a natural rubber or a mixture thereof with a synthetic rubber at a temperature of 120-250°C in the presence of a sulfur-free vulcanizer/activator system comprising a phenol resol which contains at least 90 mol.%, based on the total amount of phenols, p-(3-12C)alkylphenol and a substance or mixture of substances, which acts as a Brnsted or Lewis acid under the reaction conditions of the rubber-vulcanization.