The scientific and technological foundations of plasma synthesis of titanium diboride, including thermodynamic and kinetic conditions of boride formation during the interaction of titanium and titanium dioxide with the products of boron gasification in the stream of nitrogen - hydrogen plasma and its laws for the two options using titanium powder mix - boron and titanium dioxide - boron. Within the study of technological options the authors obtained mathematical models describing the dependence of the amount of titanium diboride and boron in synthesis products on the basic parameters. The authors examined and proposed a plausible mechanism of titanium diboride formation with the scheme “vapor - melt - crystal”, involving the condensation of titanium vapors in the form of aerosol, boriding of melt nanodroplets with borohydride and titanium - boron melt crystallization. There was conducted the complex physical and chemical certification of titanium diboride, which includes the study of the crystal structure, phase and chemical composition, dispersion, morphology and particle oxidation. The authors analyzed technological prospects to apply titanium diboride nanopowder as the main component of a wettable coating for carbon cathodes with improved physical - mechanical and barrier properties.