Additionally, the Python programming language 15 enables the easy development of GUIs, namely based on tkinter, which is the standard Python interface to the Tcl/Tk GUI toolkit. Tk/Tcl is an integral part of Python and the tkinter package is usually bundled with Python. It has been used to develop GUIs of chemoinformatics software based on RDKit. For example, Shi and Borchardt 17 combined RDKit and the tkinter module to write JRgui, a GUI program to calculate Joback and Reid group contribution molecular descriptors. The GUIDEMOL application presented in this Note relies on tkinter to build a GUI for the calculation of molecular descriptors with RDKit, as well as grid representations of 3D molecular structures. It was developed as a minimalist interface to routine chemoinformatics tasks and the calculation of well-established descriptors. The source code is available at under the three-clause Berkeley Software Distribution (BSD) license, which allows both commercial and non-commercial use, and can be very easily extended for the deployment of other molecular descriptors or as a template for GUIs to other chemoinformatics tasks.