Two closed cell aluminium foams and one open cell nickel-chromium foam were subjected to microstructural characterization, in situ fracture tests and fractography. The failure process of the open cell foam was observed to be rather ductile, while that of the closed cell foams was found to be brittle. The ductility was related to the purity of the nickel chromium alloy, resulting in necking to be the dominant source of energy dissipation during failure. The brittleness of the closed cell foams was related to the presence of precipitates and particles in the cell wall microstructure, limiting the amount of plastic dissipation. The embrittling phases were traced back to the alloy composition, viscosity enhancing additions and foaming agent.