The heat capacities of gamma-Al2O3 were measured from 50 to 700 degrees C using an HT1000 calorimeter. The heat of transformation gamma-Al2O3 to alpha-Al2O3 was directly measured using an HT1500 calorimeter. Combination of these results with the values from the literature led to Delta(f)H(m)(theta) = -(1657.2 +/- 1.5) kJ mol(-1), S-m(theta) = (52.30 +/- 2.00) J mol(-1) K-1 and Delta(f)G(m)(theta) = -(1564.2 +/- 2.0) kJ mol(-1).