Background Family caregivers of patients with severe illness and in need for a palliative care approach, face numerous challenges and report having insufficient preparedness for the caregiver role as well as a need for information and psychosocial support. Preparing to care for a severely ill family members also means becoming aware of death. Feelings of being prepared are associated with positive aspects and regarded protective against negative health consequences. Methods The study adheres to the SPIRIT-guidelines (Supplementary 1), uses a pre-post design and include a web-based intervention. Inclusion criteria are; being a family caregiver of a patient with severe illness and in need of a palliative care approach. The intervention which aims to increase preparedness for caregiving and death is grounded in theory, research and clinical experience. The topics cover: medical issues, symptoms and symptom relief; communication within the couple, how to spend the time before death, being a caregiver, planning for the moment of death and; considerations of the future. The intervention is presented through videos and informative texts. The website also holds an online peer-support discussion forum. Study aims are to: evaluate feasibility in terms of framework, content, usage and partners' experiences; explore how the use of the website, influences family caregivers' preparedness for caregiving and death; explore how the use of the website influences family caregivers' knowledge about medical issues, their communication with the patient and their considerations of the future; and to investigate how the family caregivers' preparedness for caregiving and death influences their physical and psychological health and quality of life 1 year after the patient's death. Data will be collected through qualitative interviews and a study-specific questionnaire at four time-points. Discussion This project will provide information about whether support via a website has the potential to increase preparedness for caregiving and death and thereby decrease negative health consequences for family caregivers of patients affected by severe illness. It will provide new knowledge about intervention development, delivery, and evaluation in a palliative care context. Identification of factors before death and their association with family caregivers' preparedness and long-term health may change future clinical work.