IntroductionElectroencephalographic neurofeedback (NFB), as a non-invasive form of brainwave training, has been shown to be effective in the treatment of various mental health disorders. However, only few results regarding manualised and standardised NFB trainings exist. This makes comparison as well as replication of studies difficult. Therefore, we developed a standard manual for NFB training in patients with mental health disorders attending a psychosomatic outpatient clinic. The current study aims at investigating the conduction of a standardised manual for NFB training in patients with mental health disorders. If successful, the study provides new opportunities to investigate NFB in a more controlled and comparable manner in clinical practice.Methods and analysis30 patients diagnosed with a mental health disorder will be included. After the educational interview, patients will undergo baseline diagnostics (T0). The subsequent intervention consists of 10 sessions of NFB training aiming at increasing sensorimotor rhythm and alpha-frequency amplitudes and decreasing theta-frequency and high beta-frequency amplitudes to induce relaxation and decrease subjective stress. All patients will undergo a post-treatment diagnostic assessment (T1) and a follow-up assessment 8 weeks following the closing session (T2). Changes in amplitude bands (primary outcome) will be recorded with electroencephalography during pre-assessments, post-assessments and follow-up assessments and during NFB sessions. Physiological (respiratory rate, blood volume pulse, muscle tension) and psychometric parameters (distress, perceived stress, relaxation ability, depressive and anxiety symptoms, insomnia, self-efficacy and quality of life) will be assessed at T0, T1 and T2. Moreover, satisfaction, acceptance and usability will be assessed at T1 after NFB training. Further, qualitative interviews about the experiences with the intervention will be conducted with NFB practitioners 6 months after the study starts. Quantitative data will be analysed using repeated measures analysis of variance as well as mediation analyses on mixed linear models. Qualitative data will be analysed using Mayring’s content analysis.Ethics and disseminationThe study was approved by the ethics committee of the Medical Faculty of the University of Duisburg-Essen (23–11140-BO) and patient enrolment began in April 2023. Before participation, written informed consent by each participant will be required. Results will be published in peer-reviewed journals and conference presentations.Trial registration numberProspectively registered on 28 March 2023 in the German clinical trials register, DRKS00031497.