This is the printable version of an interactive identification tool for 100 species of lichens commonly occurring in Thailand, prepared on the occasion of a workshop held in Bangkok in June 2017. Of course, this guide cannot be used to identify all lichens found in the Country, but it may be useful as a tutorial in workshops and courses for students and beginners, who will be asked to identify only the species which are included in the key. In this way, they will learn the basic terminology, and will make the first steps in lichen identification. The dichotomous key is also available in several stand-alone versions: printable, CD-Rom, and for mobile devices via the free app KeyToNature (Android and iOS). The key has been created using program FRIDA at the Department of Life Sciences of the University of Trieste (Italy), and will be further tested and implemented at the Department of Biology of the Ramkhamhaeng University, Bangkok, to encompass a broader set of species.