Smartphone technology has recently gained attention in the field of E-Mental Health research and mobile applications for measuring health-related aspects as well as mobile mental health interventions have emerged. However, little work has been done on leveraging mobile technology in combination with internet-based interventions. We argue, that mobile applications can not only enrich mental health treatments but also foster the commercial success of E-Mental Health applications. To this end, we have developed GET.ON PAPP, a mobile application for panic disorder that integrates an internet-based treatment into daily life. In this work, we present the development and structure of GET.ON PAPP and a perspective for its evaluation.