Water-blown bio-based thermoplastic polyurethane (TPU) formulations were developed to fulfill the requirements of the reactive rotational molding/foaming process. They were prepared using synthetic and bio-based chain extenders. Foams were prepared by stirring polyether polyol (macrodiol), chain extender (diol), surfactant (silicone oil), chemical blowing agent (distilled water), catalyst, and diisocyanate. The concentration of chain extender, blowing agent, and surfactant were varied and their effects on foaming kinetics, physical, mechanical, and morphological properties of foams were investigated. Density, compressive strength, and modulus of foams decrease with increasing blowing agent concentration and increase with increasing chain extender concentration, but are not significantly affected by changes in surfactant concentration. The foam glass-transition temperatures increase with increasing blowing agent and chain extender concentrations. The foam cell size slightly increases with increasing blowing agent content and decreases upon surfactant addition (without any dependence on concentration), whereas chain extender concentration has no effect on cell size. Bio-based 1,3-propanediol can be used successfully for the preparation TPU foams without sacrificing any properties. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 128: 292-303, 2013