ThermoML Opener is a software product that allows one to view ThermoML files in Microsoft Excel. It uses XSLT (eXtensible Stylesheet Language for Transformations) technology to translate a ThermoML file into an HTML file suitable for opening by Excel. The frontend is a Visual Basic standalone executable that scripts the steps of this process. That is, it opens the ThermoML file chosen by the user, scripts the XSLT translation, opens Excel, and imports the translated ThermoML file. ThermoML Opener is a component of the software infrastructure designed to support ThermoML, the IUPAC XML-based standard for thermophysical and thermochemical property data communications.