GTT - The Single Source for Thermochemistry Tools

GTT has specialized in the field of technical thermochemistry since 1983. We were among the pioneers in the practical application of thermochemistry to analyse industrial problems.

Our primary goal is to make it easy for you to take advantage of technical thermochemistry

  • for process controll
  • for product controll
  • for materials design.

We are located in Herzogenrath near Aachen, but we have a world-wide chain of agents and partners.

GTT-Technologies has its roots at the Lehrstuhl für Werkstoffchemie (Materials Chemistry) of RWTH Aachen (Aachen University of Technology).


History of GTT-Technologies

Spin-off from RWTH Aachen University

GTT-Technologies was founded in 1983 as GTT Gesellschaft für Technische Thermochemie und -physik mbH. It is a spin-off from the former Lehrstuhl für Theoretische Hüttenkunde und Metallurgie der Kernbrennstoffe (LTH, today: Materials Chemistry) of RWTH Aachen University. The earliest activities at LTH go back to the 1970s when the thermochemical database project THERDAS (Thermochemische Datenbank Anorganischer Stoffe) has been very engaged in the field of Computational Thermochemistry.

Early Data Work

The first result of this work was the printed data compilation “Thermochemical Properties of Inorganic Substances” by Ihsan Barin and Ottmar Knacke, which was later augmented by the second edition of Ihsan Barin, Ottmar Knacke and Oswald Kubaschewski. Kubaschewski also published, together with Ben Alcock, the 5th edition of “Metallurgical Thermochemistry” during that time.

Starting Computational Thermochemistry

However, first success in the field of Computational Thermochemistry only came about when in the late 1970s the database was joined with some application programs, such as Reaction (for the calculation of thermodynamic properties changes for stoichiometric reactions) or Predom (for the calculation of predominance area type of phase diagrams). The most important join was however with the Gibbs energy minimizer SOLGASMIX which had been made available to MCh (formaly LTH) by courtesy of Gunnar Eriksson, then at Umeå University. Complex gas phase equilibria as well as equilibria involving dilute metallic solutions and stoichiometric precipitates opened the door for applications in real world cases, especially in the field of ferrous metallurgy and iron based alloys.


The next step forward was taken when through the work of Philip Spencer and Klaus Hack in the early 1980s calculations with real alloys and complex slag systems were made possible. At this time Gunnar Eriksson’s involvement in the THERDAS activities had already become so strong that he finally moved to Aachen to work regularly at LTH.

Implementation on PC

In the early stages of GTT the major route to serve users was the provision of calculational services using the mainframe computer of RWTH. This was very successful in terms of the cases investigated and the improvements brought about for the end users. When in the late 1980s the computational power of PCs increased more and more, a new fruitful field for activities of GTT on the market was opened: provision of data and software for interactive calculations by the end users themselves!

Process Simulation

This field has developed more and more by the advent of even more powerful PCs and the availability of large storage capacities and high resolution graphical output devices. The ever increasing computational power has even made it possible to extract from the interactive integrated thermodynamic databank system ChemSage the core routines and to combine these into an application library for thermochemical calculations. This library named ChemApp is now being used to develop comprehensive tools for the simulation of inorganic high temperature processes. First successful applications have shown the usefulness of this method in the description of a steel converter, a waste combustion power plant, a cement kiln and a series of other applications. Also the use of rigorous computational thermochemistry from within a spreadsheet package, here in the form of the ChemSheet add-in for EXCEL by Microsoft, has proven successful as shown in wet end paper machine thermochemistry, nuclear reactor safety investigations, stack gas simulations and many other applications.

With the joining of forces during recent years with strong partners around the world, e.g. SGTE on data development, Thermfact/CRCT on the development of the interactive software FactSage and also on data, VTT Processes on the spreadsheet add-in ChemSheet and its applications in industry, SMS-DEMAG on the process simulation tool SimuSage, GTT is now set up for a strong future in the 21st century.