Abstract: The present invention relates to composition for the preparation of a polymeric foam with improved thermal properties, to a polymeric foam obtainable therefrom, and to a method for preparing such a polymeric foam each for them comprising (i) an at least essentially amorphous polymer resin and (ii) a nucleating agent. The at least essentially amorphous polymer resin is preferably polystyrene. The nucleating agent is preferably selected from the group consisting of a 1,3,5-benzenetricarboxylic acid derivative, a 5-amino isophthalic acid derivative, a 3,5,-diamino benzoic acid derivative, a 1,3,5-benzenetrisamide, a 2,4,6-trimethyl-1,3,5-benzenetrisamide, and mixtures thereof, and is preferably 1,3,5-tris(2,2-dimethylpropanamido) benzene.