A fracture criterion for rigid polyurethane foam is developed based on idealization of constituent cells by elongated tetrakaidecahedra. The ability of the proposed geometrical model to mimic the fracture characteristics of actual rigid polyurethane foam is examined and a fracture criterion derived analytically. In tandem, the fracture properties of an actual rigid polyurethane foam are obtained from mechanical tests. The fracture criterion based on the model exhibits correspondence with the behavior of actual foam. Consequently, this model constitutes a suitable basis for further investigation into the mechanical properties of actual polymeric foams.