In this paper the development process of mobile applications for the Android operating system is explained. In the first part short historical overview of Android OS development has been presented and rapid growth of the mobile applications market, that creates opportunities for making money by creating new applications documented. Like any software, Android has been improved over time, from version 1.0 created in 2008. through to the latest version 7.0 Nougat. Improvements and upgrades of each version are explained in the chronological order. Architecture of Android software stack, from the lowest Linux Kernel level, through Libraries and Application Framework levels to the applications level. The application is made in Android Studio integrated development environment for mobile applications. Features provided by the selected IDE and available tools are explained, and so are the interface for input creation and application development process. The entire development process is presented on the example of small application developed solely for this purpose.