In this volume, for the first time, a dozen of papers is collected dealing with almost all important aspects of ion cyclotron resonance spectrometry. The ICR technique was developed very rapidly in the last two decades. It seems to the editors that the method is now established well enough to dedicate a progress report to it. This report is devided into three parts: The first articles pre- sent new developments in the theory of ICR spectrometry. They are fol lowed by papers on r.ecent developments of the experimental technique. About half of the volume is dedicated to applications of ICR spectrome- try to reactivity, reaction mechanism and structure in the chemistry of thermal ions. The editors are indebted to Mrs. A. Tin for typewrfting most of the manuscript and to Mrs. E. Jacke for reproduction of Figures appearing in the volume. Hermann Hartmann, Akademie der Wissenschaften und der Literatur Mainz Karl-Peter Wanczek Institut für physikalische Chemie Universität, Frankfurt/Main Contents Line Shapes in Ion Cyclotron Resonance Spectra A. H. Huizer and W. J. van der Hart 1 Quantum Mechanical Description of Collision- Dominated Ion Cyclotron Resonance H. Hartmann and K.-M. Chung 17 Improvement of the Electric Potential in the Ion Cyclotron Resonance Cell J. Urakawa, H. Shibata and M. Inoue 33 Thermodynamic Information from Ion-Molecule Equilibrium Constant Determinations S. G. Lias 59 Pulsed Ion Cyclotron Resonance Studies with a One-Region Trapped Ion Analyzer Cell R. T. McIver, Jr.