The kinetics of molybdenite roasting was studied by non-isothermal TGA-DTA with heating rate 10 degrees C min(-1). Mechanical activation of molybdenite was accomplished via milling in a planetary mill under air atmosphere. Mechanical activation decreased the ignition temperature of reaction from 470 to 180 degrees C after 36 h of milling. The model-fitting kinetic approach has been applied to TGA data. The reaction mechanism for non-activated molybderiite was determined to be chemically controlled with E = 34.25 kcal mol(-1) and A = 2 x 10(8) s(-1). In the activated molybdenite the reaction mechanism changed to diffusion control with E = 60.55 kcal mol(-1) and A = 6 x 1019 s-1. (c) 2006 Elsevier B.V. All rights reserved.