Kotlin is a modern programming language that tries to address some of the drawbacks of Java, while keeping all the advantages of Java. It promises concise and functional code with new concepts for easier implementation of common structures. Kotlin's popularity is growing fast, especially in the development of Android mobile applications, where the latest versions of Java are not supported. The goal of this thesis was to present Kotlin programming language and use it practically in the development of a mobile food ordering system. The system consists of a web service, a mobile application that enables users to easily create orders and a web application that enables restaurant employees to manage received orders. We developed the web application and web service in Spring Boot framework, using Kotlin and HTML and CSS technologies. For storing the data, we used MySQL relational database. We developed the Android mobile application according to Google guidelines, using MVVM architectural pattern.