The dissociation energy of the intermetallic molecule AuMg was for the first time determined by the Knudsen-effusion mass spectrometry technique. Partial pressures of Au(g), Mg(g), AuMg(g) and Au,(g) species produced under equilibrium vaporization of an appropriate alloy were monitored in the temperature range 1870-2333 K. The collected data were analyzed by the second- and third-law methods for the gaseous equilibria AuMg(g) = Au(g) + Mg(g) and AuMg(g) + Au(g) = Au(g) + Mg(g). The selected value for the dissociation energy of AuMg at 0 K is Ddegrees(0)(AuMg) 175.4 +/- 2.7 kJ/mol. (C) 2003 Elsevier Science B.V. All rights reserved.