[en] Single crystals of LaB₆ were prepared by float zone refining of hot pressed blocks of LaB₆. The orientations studied were (001), (110), and a high index plane. The resulting crystals and the as-received material were chemically analyzed by vacuum fusion, combustion analysis, self-arc mass spectroscopy, and wet chemical analysis. The first two provided accurate analysis for O, N, H, and C. The remaining elements except for La and B were determined by mass spectroscopy. The wet chemical analyses determined the B/La ratio. Two batches of as-received material had B/La ratios of 6.0 and 5.8, respectively. Slightly lower B/La ratios were obtained in the single crystals grown by the float zone technique from these materials. The single crystals were further characterized by measurements of lattice parameter and density. Work function values were determined by the FERP method and the thermionic method. Work function measurements in conjunction with Auger analysis of the crystals provided insight into the electron emission character of LaB₆. Results indicate that for maximum emission from a crystal plane a proper heat treatment is necessary. Brightness of the crystals was measured in a Cambridge S-4 scanning electron microscope using a Broers type gun. Results show that a brightness of 10⁶ amp/cm² steradian (20kV) may be achieved with a single crystal LaB₆ cathode operating at a temperature of 1900⁰K which corresponds to a lifetime greater than 500 hrs for 1 mm cathodes