BACKGROUND: Cognitive Behavioural Therapy for psychosis (CBTp) has an established evidence base and is recommended by clinical guidelines to be offered during the acute phases of psychosis. However, few research studies have examined the efficacy of CBTp interventions specifically adapted for the acute mental health inpatient context with most research trials being conducted with white European community populations. AIMS: The aim of this study is to conduct a pilot randomised controlled trial (RCT), which incorporates the examination of feasibility markers, of a crisis-focused CBTp intervention adapted for an ethnically diverse acute mental health inpatient population, in preparation for a large-scale randomised controlled trial. The study will examine the feasibility of undertaking the trial, the acceptability and safety of the intervention and the suitability of chosen outcome measures. This will inform the planning of a future, fully powered RCT. METHODS: A single-site, parallel-group, pilot RCT will be conducted examining the intervention. Drawing on principles of coproduction, the intervention has been adapted in partnership with key stakeholders: service users with lived experience of psychosis and of inpatient care (including those from ethnic minority backgrounds), carers, multi-disciplinary inpatient clinicians and researchers. Sixty participants with experience of psychosis and in current receipt of acute mental health inpatient care will be recruited. Participants will be randomly allocated to either the crisis-focused CBTp intervention or treatment as usual (TAU). DISCUSSION: Findings of this pilot RCT will indicate whether a larger multi-site RCT is needed to investigate the efficacy of the intervention. If the initial results demonstrate that this trial is feasible and the intervention is acceptable, it will provide evidence that a full-scale effectiveness trial may be warranted. TRIAL REGISTRATION: This trial has been prospectively registered on the ISRCTN registry ( ISRCTN59055607 ) on the 18th of February 2021.