Psychroisis, a complex phenomenon involving the interaction of thermal and psychrometric factors, has significant implications in various fields, including building design, HVAC engineering, and environmental science. This paper presents the development of a ThermExcel programme for psychroisis, a comprehensive tool designed to analyze and visualize thermal and psychrometric processes. The programme utilizes an Excel-based interface, integrating Visual Basic for Applications (VBA) and thermodynamic property calculations to provide a user-friendly platform for engineers, researchers, and students. The ThermExcel programme for psychroisis enables the calculation of psychrometric properties, plotting of psychrometric charts, and simulation of various thermal and psychrometric processes.