Prospects are discussed for the use of BeO-ceramic in electronic and other fields of technology and special instrument building. With use of BeO-ceramic in electronic technology one of the main parameters is its high thermal conductivity. Analysis of publications shows that BeO-ceramic in the range 300 -500 K exhibits the highest thermal conductivity among all ceramic materials used in electronic technology. Results are provided for a study of the thermal conductivity of 170 ceramic specimens made from BeO-ceramic with an identical configuration and dimensions prepared from one batch of BeO starting powder. It is established that the average size of microcrystals and the density of specimens have a defining effect on thermal conductivity.One of the most important properties of ceramic based on beryllium oxide is its high thermal conductivity: among other well-known oxide ceramic materials (Al 2 O 3 , MgO, SiO 2 , ZrO 2 , ThO 2 , etc.) BeO-ceramic has the highest thermal conductivity, by a factor of three than for ceramics based on MgO, and by a factor of 4 -6 or more, than for ceramics based on Al 2 O 3 [1]. The thermal conductivity of BeO-ceramic is 230 -330 W/(m × K) depending on its density, and it exceeds the thermal conductivity of beryllium metal and other metals with the exception of gold, silver and copper [1,2].Beryllium ceramics exhibit not only high thermal conductivity, but also a unique combination of other physicochemical properties such as high chemical, thermal, radiation resistance, a considerable specific volumetric resistance, low dielectric losses, transparency for vacuum, ultraviolet, visible, infrared, x-ray and ultrahigh frequency (UHF) radiation. This makes BeO-ceramic a promising material for use in contemporary electronics, new fields of technology and special instrument building [2], and in high-current UHF technology there is no alternative to BeO-ceramics.Currently objects made from BeO-ceramic are used extensively as:-refractory material in special metallurgy with melting of chemically corrosive substances, pure, ultrapure, expensive and refractory metals (beryllium, uranium, plutonium, iron, nickel, and molybdenum, and also high-purity gold, silver, platinum, lead, cobalt, silicon and titanium); -structural material in electronic technology making it possible to miniaturize electronic and electrical circuit components;-dielectric discharge channels of resonators, shells of active elements, hollow dielectric waveguides for waveguide gas lasers, and also optical quantum generators of a broad spectral range, i.e. from ultraviolet (UF) to infrared (IR) regions of the spectrum; -insulators and heat conductors, substrate-crystal holders of powerful UHF transistors and ultra-large integral circuits, microcircuits; -windows and insulators for high-current UHF technology, powerful on-board radars;-structural elements for travelling-wave lamps; -powerful heat transfer elements in cryogenic technology; -material for heat release of a matrix element in nuclear reactors;-neutron reflectors, neut...