Medical researchers are exploring the potential of patients’ mobile phones and wearables for medical studies. The contribution of volunteers in a form of citizen science, where citizens donate their data for research purposes, can enable studies on a large scale. This research area, known as mobile health, often relies on shared data such as tracked steps or self- reporting forms. Privacy, transparency and trust play a fundamental role in the interaction of users with related platforms that agglomerate medical studies.This project explores privacy concerns of potential users of mobile health citizen science apps, summarises similar user patterns and analyses the impact of transparency enhancing tools on the users’ trust. In this context, a prototype with different features that aim to increase the transparency is designed, tested and evaluated. The results indicate how users perceive the importance and the generated trust of the proposed features and provide recommendations for data donation platforms.