Abstract: The present invention relates to a process for the preparation of a foamed article having a foam density of less than 180 kg/m3 and an average cell diameter of less than 1.5 mm comprising the extrusion of a molten semi-crystalline thermoplastic resin composition in the presence of a foaming agent, with the semi-crystalline thermoplastic resin composition comprising a polymeric epoxide containing at least two epoxide groups being a copolymer of a monomer mixture comprising at least one C10 to C18-olefin and at least one ethylenically unsaturated compound comprising an epoxide group. The process results in the preparation of foamed articles having a regular and homogeneous structure. Another advantage of the present invention is that it is not necessary anymore to add a compound of Group Ia, IIa, or IIIa of the Periodic Table, such as LiCl, to the extrusion process.