COSMOtherm: Predicting Solutions since 1999

COSMOtherm is the universal tool for predictive property calculation of liquids, and combines quantum chemistry and thermodynamics in a unique fashion. It calculates the chemical potential of almost any molecule in almost any pure or mixed liquid at variable temperature, i.e. it predicts how happy a molecule is in a certain liquid environment. This is the key for the prediction of a multitude of properties required in industrial applications or academic research, including solubility, partitioning, vapor pressure, and complete phase diagrams. In contrast to several other available methods COSMOtherm is able to predict properties as function of concentration and temperature by applying thermodynamically consistent equations.

A. Klamt, CEO

The Original

COSMOtherm is the first publicly available and most advanced implementation of the COSMO-RS theory, which was published by A. Klamt at Bayer in 1995. He started COSMOlogic a few years later to focus on the advancement of COSMO-RS and COSMOtherm. COSMOtherm has found widespread use in many industrial branches related to chemistry, pharmaceutics, consumer goods or fragrances.

Predictable properties

  • Solubility of liquids, solids and gases
  • Activity coefficients, two-phase partitioning (e.g. LogP), liquid extraction
  • Conformer relevance in different mixtures
  • Phase behavior: liquid-liquid, liquid-vapor and liquid-solid equilibria
  • Vapor pressures, free energy of solvation, Henry's law constant
  • pka, dependence of chemical reaction equilibria on the solvent
  • Energy of transfer to a flat liquid-liquid interface
  • Micelle and membrane partitioning
  • Interfacial tension, adsorption and environmental properties

Ready out of the box

COSMOtherm features an easy to use graphical interface to allow users to focus more on research and less on the software. In addition, the completely input file-oriented command line version allows seamless integration into existing workflows or batch processing. The greatest advantages of COSMOtherm are its general applicability and its high predictivity. Once integrated into the workflow, it can be applied to almost the complete range of organic chemistry without needing a scientist to think about missing parameters or applicability for a specific case.

Fewer complications

  • No missing parameters
  • No case-specific choices of any kind
  • Predictivity far beyond fitting sets
  • Multifunctional and complex compounds are welcome
  • Results within seconds or minutes
    (a time-consuming DFT calculation has to be conducted for each molecule once, the results are then stored and can be reused for all properties and mixtures later on)
COSMOtherm Workflow


  • Limited to incompressible liquids, sufficiently below the critical point
  • Gas phase chemical potential is only valid for ideal gases
  • Polymers can only be predicted as solvents for small molecules
  • Long-range interactions of ions are missing ( e. g. Debye-Hückel term)

Comparison to other methods

Please find a comparison to other relevant methods:


Learn more about COSMO-RS.
The original publication on COSMO:
DOI: 10.1039/P29930000799