The kinetic energy of Positroniurn (Ps) emitted from the surface of MCP (Micro channel Plate) bombarded by slow positrons is measured. Ps work functions of many materials are negative, once they formed will come out with the kinetic energy of the magnitude of the work function of the corresponding material. The kinetic energy of the Ps was obtained by measuring the time-of-flight of the ortho-Ps. In order to confirm the constant kinetic energy target positions are shifted in several distances. The data are consistent with a general description of Ps production resulting from common interactions with the traversed material.