This paper presents recent results of foam extrusion of thermoplastic cellulose acetate (CA) using HFO 1234ze as low global warming blowing agent and talc as nucleating agent. Foam extrusion behavior, physical foam properties, and foam morphologies were studied in detail with respect to blowing agent concentration and talc content. Depending on these parameters, thermoplastic CA exhibits excellent foam extrusion performance with good expansion behavior at the die. Talc as nucleating agent results in homogeneous fine foam morphologies with closed cells [i.e., Fig. 3(3)]. Depending on the blowing agent content and talc content, average cell size ranges from 1 to 0.12 mm and foam density ranges between 100 and 400 kg/m3.