Na-, K-, Cl-, and S-species released during thermal conversion of coal can cause several problems such as fouling, slagging and corrosion, especially in gas turbines and heat recovery systems. To reduce this problems an enhanced understanding of the underlying release mechanisms for Na-, K-, Cl-, and S-species is needed. Therefore, basic investigations have been performed in an atmospheric lab-scale tube furnace at 1400 degrees C under gasification and combustion conditions. Hot gas analysis has been carried out by molecular beam mass spectrometry. The release of H2S, HCl, K+, NaCl, COS, and SO2 has been qualitative and quantitative analysed and correlated with the coal composition. The results show a strong dependence of coal composition and reaction atmosphere on the release of Na-, K-, Cl-, and S-species. Additionally, thermodynamic equilibrium calculations with the software package FactSage 5.4.1 have been undertaken for comparison with the experimental results. (C) 2010 The Combustion Institute. Published by Elsevier Inc. All rights reserved.