Introduction: Obsessive-compulsive disorder (OCD) is a debilitating heterogeneous condition and one of the 10 leading causes of disability worldwide, affecting approximately 2%-2.3% of the population. However, there is a long delay in seeking treatment, and between 38% and 89.8% of OCD sufferers neither ask for nor receive treatment for their symptoms. Studies on OCD report that insufficient mental health literacy about OCD and the associated stigma would explain the delayed treatment-seeking behavior of OCD patients. With the aim of increasing OCD mental health literacy and reducing the associated stigma, a gamified mental health mobile application (app) called esTOCma was developed. The objective of the study is to describe the randomized control trial that will test the efficacy of the esTOCma app in a Spanish non-clinical sample. The trial is registered in ClinicalTrials.gov with the identifier NCT04777292. Method: A total of 300 participants from the community will be randomly allocated to one of two conditions: undertaking immediate-use or delayed-use (waiting list control group) of the esTOCma mobile app. In this app, participants are asked to fight the OCD stigma monster in ten missions on 8-10 days. They are asked to liberate 10 characters from the OCD stigma monster called EsTOCma. The app is organized in 10 missions with three levels that involve different methodological approaches: psychoeducation, contact, and cognitive restructuring. Furthermore, participants will be asked to complete a set of questionnaires at baseline, at the end of the app, and at 3 and 6 months from baseline: Mental Health Literacy about OCD (MHL-OCD), Attribution Questionnaire (AQ-27), Social Distance Scale (SDS), and General Help-Seeking questionnaire (GHSQ). Results: It is expected that after using the app, participants will have greater knowledge about obsessive-compulsive disorder (MHL-OCD), be more likely to ask for help when having OCD symptoms (GHSQ), and show lower stigma attitudes (AQ-27) and social distance (SDS), and these changes will be maintained at 3- and 6-month follow-ups. Discussion: If esTOCma proves to be effective, widespread use of the app could improve access to mental health services and early help-seeking in people suffering from OCD, which, in turn, could reduce the personal and financial costs associated with OCD. Acknowledgment. Grant RTI2018-098349-B-I00 provided by Ministry of Science and Innovation – State Research Agency of Spain, and co-funded by the European Union European Regional Development Fund (ERDF).