Frankfurt am Main – The MathCityMap-Project was developed by combining the concept of a math trail program with advanced mobile technology. It aims at providing a new approach to promote student motivation to engage in meaningful mathematical activity. An explorative study was conducted as a pilot using nine secondary schools in the city of Semarang, Indonesia, and 272 students and nine teachers were included. Using self-determination theory as a framework, we explored the motivation of students to engage in mobile app-supported math trail activity. Data collection procedures comprised observation, interviews, questionnaires, and student work analyses. Findings indicate that intrinsic motivation and identified regulation established an essential part of students’ motivation to engage in this activity. The design of the learning environment, the use of mobile app, and the value of the mathematical task have contributed to this result.