The reduction of silver(I) oxide to metallic silver by gaseous hydrogen was studied by means of thermogravimetric analysis, at constant heating rates in the range 2.5-30 degrees C min(-1). Under these conditions the reduction process completed in the temperature range 60-190 degrees C. Both the expanded Friedman's isoconversional method and Kissinger's method were used to determine the activation energy, and very similar values, 59.6 kJ mol(-1) and 59.7 kJ mol(-1), respectively, were obtained. The expanded Friedman's isoconversional method, involving the first order reaction model, enabled the satisfactory fit of the experimental data. (C) 2011 Elsevier B.V. All rights reserved.