Various electrolytes were used to deposit LaB6on carburized tantalum by the cataphoretic method. The effect of four electrolytes viz., HCl, NH4NO3, La(NO3)3, and HNO3on LaB6coatings has been investigated. It is observed that use of HCl as an electrolyte provides LaB6coatings with small grain size, low porosity, good adhesion, and ability to withstand a large number of thermal shocks. These properties make HCl the most suitable electrolyte for cataphoretic deposition of LaB6for thermionic emission.