Crack growth along porous ceramic layers was studied experimentally. Double cantilever beam sandwich specimens were loaded with pure bending moments to obtain stable crack growth. The experiments were conducted in an environmental scanning electron microscope enabling in situ observations of various mechanisms associated with crack growth. The macroscopic fracture energy of the interface between dense lanthanum strontium chromite and a porous lanthanum strontium manganite was measured to lie in the range of 1.4-3.8 J/m(2). Several micromechanisms were observed ahead of, or in the wake of, the crack tip. The measured variation of the fracture energy along the crack length may be attributed to such phenomena.