The hydrogen anion (H-) and other anionic species (O-, OH-, e(-)) in the gas phase. emitted from the synthesized crystal surface of 12CaO center dot 7Al(2)O(3)-H- (C12A7-H-), have been observed. The emission intensity of all the anionic species strongly depends on the sample surface temperature and the extraction field. H- has the highest emission branch ratio, and the extraction field can reduce its apparent activation energy. H- emission current at a mu A/cm(2)-level has been achieved, which is about 4 orders of magnitude higher than that obtained from the thermal desorption process of CaH2. The observed anions of H- and OH- are attributed to their migration from the C12A7-H- cages onto the surface [i.e., Y-(cages) -> Y-(surface) -> Y-(gas phase) (Y = H, OH)]. The weak O- and electron emission would both arise from the dissociation of O2-: O2-(surface) -> O-(surface) + e(-)(surface) -> O-(gas phase) + e(-)(space).