The values of the formation heat of 15 aluminium-gold alloys have been determined. The measurements were carried out by use of a “small furnace calorimeter” in which compacts of the mixed powders of the metals were heated electrically until the strong exothermic reaction set in. The results are plotted in a graph and briefly discussed. Typical values are: AuAl₂ : ∆H = - 10.1 Kcal/g.at; AuAl : ∆H = - 9.2 Kcal/g.at, and AU₂Al : ∆H = - 8.3 Kcal/g.at. (± 0.5). The different alloys were checked against chemical alterations and composition changes carrying out, on several portions of each sample, chemical analysis and micrographic and X-ray examination. The data are reported and some microphotographs are included.