We demonstrate a new method for thermal analysis of nanogram quantities of material using a micromechanical thermogravimetric technique. The cantilever-type device uses an integrated piezoresistor to sense bending and simultaneously to ramp the temperature and control temperature cycles. It has a mass resolution in the picogram range. A quantitative analysis of the dehydration of copper-sulfate-pentahydrate (CuSO4. 5H(2)O) is presented. The technique outperforms current thermogravimetric approaches by five orders of magnitude. (C) 1998 Elsevier Science B.V. All rights reserved.