Phase diagrams are representations of the sate of a material as a function of temperature of thee constituent components. Multi-components phase diagrams are useful for alloy development processing and understanding. They are considered as roadmaps in design of new materials used in technology. To establish phase diagrams we usually use a thermodynamic approach called CALPHAD (CALculation PHase Diagrams) based on the knowledge and minimization of the Gibbs energy of all phases taking part in the system. We can obtain the Gibbs energy of each phase by using experimental methods (calorimetry). We can also use theoretical method (ab-initio) or a semiempirical model of Miedema. We reviewed and used three calorimetric methods: direct reaction, progressive precipitation and indirect mixing calorimetry. We obtained at high temperatures the enthalpies of formations of eight compounds: Ga3Mo, Ga5Mo, GaNb3, Ga5Nb4, Ga3Nb,  -GaCr3,  -GaCr3 and Ga4Cr. Their values were compared to those estimated theoretically, reviewed and commented. In addition to their exploitation to establish phase diagrams, these data permits to improve thermodynamic models and understand the behaviours of gallium towards the three transition metals molybdenum, niobium and chromium. This procedure can be applied do ternary compound if needed.