Introduction: Bereaved parents have elevated risk to develop mental health problems, yet, few studies have evaluated the effect of psychosocial interventions developed for bereaved parents. Cognitive behavioral therapy (CBT), both face-to-face or digitally delivered, has shown to be an effective intervention for prolonged grief symptoms. Self-help mobile apps offer various advantages and studies show improved mental health after app interventions. No app has yet been evaluated targeting prolonged grief in bereaved parents. Therefore, the aim of this planned study is to develop and examine the effectiveness of a CBT-based mobile app, called My Grief, in reducing symptoms of prolonged grief, as well as other psychological symptoms, in bereaved parents. Another aim is to assess users’ experiences and adverse events of My Grief.

Methods and analysis: We will conduct a two-armed randomized waitlist-controlled trial. Parents living in Sweden, who lost a child to cancer between one and ten years ago, with elevated symptoms of prolonged grief, will be recruited to participate in the trial. The content of My Grief covers four main domains (Learn; Self-monitoring; Exercises; Get support) and builds on principles of CBT and the proven-effective PTSD Coach app. Participants in the intervention group will fill out online questionnaires at baseline and at 3-, 6- and 12-months follow-ups, and the waitlist-controls at baseline and at 3 months. The primary outcome will be prolonged grief symptoms at the 3 months follow-up. Secondary outcomes are posttraumatic stress and depression symptoms, quality of life, and cognitive behavioral variables (i.e., avoidance, rumination, negative cognitions).

Ethics and dissemination: Ethical approval has been received from the Swedish Ethical Review Authority (project no. 2021-00770). If the app is shown to be effective, the app will be made publicly accessible on app stores, so that it can benefit other bereaved parents.

Trial registration: Clinicaltrials.gov, identifier: NCT04552717.