The main objective of this thesis has been to use Kotlin programming to develop an Android application that will help international newcomer students. The result of the thesis project was an Android application which I named “Debbook” was successfully developed and tested on multiple Android devices. Debbook is a collection of experiences from more than 20 students who have spent at least 3 years in Debrecen. This thesis is about an Android application typed in Kotlin programming language. The application "Debbook" is a guide to the international newcomer students in University of Debrecen to assist them getting to know the city of Debrecen from getting to know the Hungarian food and Debrecen transportation system to helping them finalizing their official documents in Hungary and providing all useful info about the faculties, etc. The thesis is divided into 6 main chapters. An introduction to mobile application development and the issue to be resolved, Android applications development details, literature review for the research, Research methodology and more details about the compiler, the results, and a conclusion.