In this work, micro- and nanocellular acrylonitrile-butadiene-styrene (ABS) foams were prepared by using sub- and supercritical CO2 as blowing agents. The sorption kinetics at 10 MPa was first measured. The sorption amount depended on the saturation temperature Arrheniusly. The diffusivities did not follow the Arrhenius relation. This relation was interpreted by a retrograde behavior of ABS/CO2 system. From the kinetics, ABS discs were saturated at 10 MPa at the temperatures from -20 degrees C to 40 degrees C, and foamed at the foaming temperature of 20 degrees C-80 degrees C. A network of closed cells with a diameter of 600-700 nm and nanopores with a diameter of 100 nm were observed in the foam obtained at low saturation temperatures and high foaming temperatures. The closed cell densities were in a range from 1.12 x 10(12) - 9.87 x 10(12) cells/cm(3) and an experimental correlation based on the CNT model was used to fit the data. (C) 2017 Elsevier B.V. All rights reserved.