Thermal decomposition of bis(tetraethylammonium) tetrachloroferrate(II) has been studied using the TG-FTIR, TG-MS and DTA techniques. The measurements were carried out in an inert atmosphere over the temperature range of 293-1073 K. The solid products of the thermal decomposition were identified by the FT-FIR, Mossbauer spectroscopy as well as the X-ray powder diffractometry. The influence of the oxidation state and the nature of a metal on thermal transformation profiles of analogous complexes have been discussed. (C) 2008 Elsevier B.V. All rights reserved.