Aims and objectives To better understand and identify vulnerabilities and risks in the ICU patient discharge process, which provides evidence for service improvement. Background Previous studies have identified that 'after hours' discharge and 'premature' discharge from ICU are associated with increased mortality. However, some of these studies have largely been retrospective reviews of various administrative databases, while others have focused on specific aspects of the process, which may miss crucial components of the discharge process. Design This is an ethnographic exploratory study. Methods Distributed cognition and activity theory were used as theoretical frameworks. Ethnographic data collection techniques including informal interviews, direct observations and collecting existing documents were used. A total of 56 one-to-one interviews were conducted with 46 participants; 28 discharges were observed; and numerous documents were collected during a five-month period. A triangulated technique was used in both data collection and data analysis to ensure the research rigour. Results Under the guidance of activity theory and distributed cognition theoretical frameworks, five themes emerged: hierarchical power and authority, competing priorities, ineffective communication, failing to enact the organisational processes and working collaboratively to optimise the discharge process. Issues with teamwork, cognitive processes and team members' interaction with cognitive artefacts influenced the discharge process. Conclusion Strategies to improve shared situational awareness are needed to improve teamwork, patient flow and resource efficiency. Tools need to be evaluated regularly to ensure their continuous usefulness. Relevance to clinical practice Health care professionals need to be aware of the impact of their competing priorities and ensure discharges occur in a timely manner. Activity theory and distributed cognition are useful theoretical frameworks to support healthcare organisational research.