BACKGROUND: The success of HIV treatment hinges on consistent adherence to antiretroviral therapy (ART). OBJECTIVES: To conduct a longitudinal pilot study to assess the feasibility, acceptability and effectiveness of a mobile app to improve ART adherence. METHOD: This study included adults living with HIV and using ART, who were allocated into two groups according to their willingness to use the app: users of the mobile application for ART management (Mobile) and non-users (Control). The application was developed by the researchers, and uses an alarm system to record ART use. Adherence was also assessed using the ' RESULTS: A significant difference in adherence was observed between the Mobile and Control groups ( CONCLUSION: The application was not effective in improving ART adherence and showed low viability, but was considered acceptable among the participants.