Pore-boundary separation in ZnO and 99.95ZnO .0.05Bi(2)O(3) (in mol%) specimens during sintering at 1200 degreesC was investigated. In pure ZnO specimens, pores were attached to the grain boundaries and disappeared during the final stage of sintering, In the Bi2O3-doped specimens, on the other hand, many pores were separated from the boundaries and trapped inside the grains. Observation using transmission electron microscopy showed that a thin layer of Bi2O3-rich phase existed at the boundaries in the Bi2O3-doped specimens, The pore separation in 99.95ZnO .0.05Bi(2)O(3) specimens was explained in terms of the dihedral angle change and the high mobility of a Liquid film boundary,