A hybrid numerical-experimental approach is used to characterize the macroscopic mechanical behavior of polymeric foams. The method is based on microstructural characterization of foams with X-ray computed tomography (CT) and conversion of the data to finite element (FE) models. The 2D models are created from a 3D close-celled foam and subjected to compression loads. Since the large strain regime is explored, contact between elements is incorporated. It is shown that, for calculating the effective Young's modulus, a model consisting of at least 11(2)-12(2) cells in the model should be used, whereas for the large strain regime 12(2)-14(2) cells in the model are needed. Discretization had a significant influence on the results, where relatively coarse elements caused loss of connectivity in the cell walls and thickening of the cell walls. It is shown that at least three to four elements should be taken over the thickness of the cell walls for these structures. Finally, a good qualitative agreement is observed between the deformations found with the FE models and in situ compression experiments of an open-celled foam during X-ray CT. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1526-1534, 2010