Mobile robots are increasingly used in our everyday life to autonomously realize missions. A variety of languages has been proposed to support robotic experts in the systematic development of robotic applications, ranging from logical languages with well-defined semantics to domain-specific languages with user-friendly syntax. Both have distinct advantages, however, developing a language that combines them to specify robotic missions remains an elusive task. We present the novel language PROMISE that enables domain experts to specify missions on a higher level of abstraction for teams of autonomous robots in a user-friendly way, while having well-defined semantics. Our ambition is to permit users to specify high-level goals instead of a series of specific actions the robots should perform. The language contains a set of atomic tasks that can be executed by robots and a set of operators that allow the composition of these tasks in complex missions. The language is supported by a standalone tool that permits mission specification through a textual and a graphical interface and that can be integrated within a variety of frameworks. We integrated PROMISE with a software platform providing functionalities such as motion control and planning. We conducted experiments to evaluate the correctness of the specification and execution of complex robotic missions with both simulators and real robots. We also conducted two user studies to assess the simplicity of PROMISE. The results show that PROMISE effectively supports users to specify missions for robots in a user-friendly manner.