AbstractIntroductionDifferent outcomes are reported in randomised clinical trials (RCTs) in intensive care unit (ICU) patients, and no core outcome set (COS) is available for ICU patients in general. Accordingly, we aim to develop a COS for ICU patients in general.MethodsThe COS will be developed in accordance with the Core Outcome Measures in Effectiveness Trials (COMET) Handbook, using a modified Delphi consensus process and semi‐structured interviews involving adults who have survived acute admission to an ICU, family members, clinicians, researchers and other stakeholders. The modified Delphi process will include two steps. Step 1: conduction of a modified Delphi survey, developed and informed by combining the outputs of a literature search of outcomes in previous COSs and semi‐structured interviews with key stakeholders. We plan at least two survey rounds to obtain consensus and refine the COS. Step 2: a consensus process regarding instruments or definitions to be recommended for the measurements of the outcomes selected in Step 1. A ‘patient and public involvement panel’ consisting of a smaller group of patients, family members, clinicians and researchers will be included in the development, analysis and interpretation of the COS.DiscussionThe outlined multiple method studies will establish a COS for ICU patients in general, which may be used to increase the standardisation and comparability of results of RCTs conducted in patients in the ICU setting.