Hydrogen isotopes sources with pressure up to several thousand atmospheres are required to pursue some investigations in nuclear and thermonuclear processes. Investigations are performed in mixtures of all three hydrogen isotopes. Stringent requirements are placed on such sources. Primarily, this is reliability and safety, purity of supplied gas, possibility of smooth pressure control, minimal dimensions and the ease to operate. Vanadium-base thermodesorption sources meet these requirements. Literature data on equilibrium pressures of hydrogen isotopes desorption over vanadium dihydride phase have been reviewed. It has been shown that in data analysis, gas nonideality at high pressure should be taken into account. In particular, when showing temperature dependencies of desorption equilibrium pressures it is reasonable to use appropriate value of fugacity. The paper presents temperature dependencies of protium and deuterium fugacity over corresponding dihydride vanadium phases in the range of 300-635K, determined using experimental data of the authors. Temperature dependence of tritium fugacity over dihydride vanadium phase at 273-483K determined using experimental data of the authors and available literature data are also presented. A series of vanadium-base thermodesorption high-pressure hydrogen isotopes sources have been developed in RFNC-VNIIEF using of the obtained dependencies. Schemes of sources for research in fundamental science are presented.