A process for production of expanded thermoplastic elastomer beads in the presence of a gaseous medium that surrounds thermoplastic elastomer beads. The process comprises a) an impregnating step, in which the gaseous medium has an impregnating temperature Ta, and the absolute pressure of the gaseous medium is greater than ambient pressure, the thermoplastic elastomer beads impregnated with a blowing agent, b) an expanding step, in which the thermoplastic elastomer beads expand as they are exposed to a pressure reduction at a first expanding temperature Tb, and c) optionally a fusing step, in which the expanded thermoplastic elastomer beads are fused together at a fusing temperature Tc to form at least one shaped part.