A cesium-diode thermionic converter suitable for laboratory instruction is described. The construction of this converter employs only simple glass-blowing techniques so that it can be easily fabricated in a moderately, well-equipped physics laboratory. The use of kovar-to-glass seals and lead-glass sections has been completely eliminated, and the use of oxide glass-to-metal seals has been minimized in the construction of the converter, thereby significantly reducing the probability of cesium attack in seal areas which would seriously limit the useful lifetime of the device. Many interesting and instructive experiments involving thermionic power generation, arc-mode or ignited operation, spectroscopic studies, ion production on high work function surfaces, and the determination of converter current-voltage characteristics can be conducted with this device.