Psychiatric conditions are a relatively common source of subjective distress. These conditions are often associated with functional and vocational impairment, thereby yielding challenges and costs to society. The last decades have witnessed a rapid increase in the prevalence of smartphone use. Meanwhile, different mental health mobile applications have been developed, either for stand-alone use or as adjuncts to existing therapy. Results of recent meta-analyses indicate that app-supported smartphone interventions can affect common mental health problems, and that therapist guidance and engagement reminders bolster the effectiveness of these interventions. The purpose of the present thesis was to trace and describe users’ experiences with a mobile app that was constructed according to a widely used schema psychotherapy technique, the mode flashcard. A mobile app compatible with Android-based user interface was constructed for the purpose of the present study. This app was piloted with one cognitive psychotherapist and three patients as part of their routine psychotherapy. Interviews were used as data collection method. The questions of this semi-structured interview addressed themes such as personal experience of app-assisted therapy, and qualities requested for a successful app. The data consists of answers to this in-depth interview and was analyzed using qualitative content analysis. The mode flashcard mobile app was perceived to facilitate between-session organization of distressing experiences, promote reflection on mental contents, aid in recalling, and facilitate recruitment of own, healthy resources at difficult moments. In terms of quality features requested for the app, user-friendliness and a visually appealing outlook were mentioned. These appeared to be prerequisites for a user to stay motivated with app use.