The paper presents peculiarities of the technology for creating a small interelectrode spacing in thermionic converters (TIC) using two-phase graphite-cesium and graphite-cesium-barium systems.Optimum conditions are discussed for cesium and barium intercalation into oriented graphite (load-bearing member) placed inside the converter interelectrode gap to obtain a stable ultra-small spacing.Principle design diagrams of a close-spaced TIC are presented, and their basic technical characteristics are assessed.The analytical relationship between the members of the load-bearing unit based on the graphite-cesium system and the TIC interelectrode spacing being formed is established from calculations and experiments.