Aim The aim of the study was to describe nursing teams' theoretical knowledge of delirium and their perceptions of the way in which it is handled in acute inpatient units. Design This is a descriptive cross‐sectional study using a questionnaire comprising ten questions on knowledge and seven on perception. Methods The sample consisted of 216 professionals working at a hospital complex in Madrid, Spain. Descriptive and non‐parametric bivariate analyses were performed for a p < .05. Results Fifty‐three point two per cent of staff possessed sufficient theoretical knowledge, and this figure rose significantly among professionals with more years of experience. Areas for improvement in theoretical knowledge included the use of therapeutic immobilization, screening scale, subtypes of delirium and precipitating factors. Sixty‐eight point five per cent of staff perceived their knowledge as fair, 50% agreed that delirium was underdiagnosed and 48.1% agreed that preventive measures were only occasionally taken. Perceived barriers included lack of training, work overload, ineffective coordination and lack of standardized protocols.