Background  Burnout has been recognised as an important stress‐related problem for employees working with people with intellectual disability. Researchers have been troubled by some of the psychometric limitations of the questionnaires developed to evaluate burnout. This study was designed to assess the psychometric properties of the Spanish Burnout Inventory.Method  The sample consisted of 697 Spanish employees working in intellectual disability services. The instrument is composed of 20 items distributed in four dimensions: Enthusiasm towards the job, Psychological exhaustion, Indolence and Guilt. The psychometric properties were examined through the following analyses: confirmatory factor analysis and reliability. To assess the factorial validity of the Spanish Burnout Inventory, four alternative models were tested.Results  The four‐factor model obtained an adequate data fit for the sample. The four sub‐scales exhibited high reliability, with Cronbach alphas exceeding the critical value of 0.70.Conclusions  This study provides evidence showing the adequate psychometric properties of an alternative burnout measure that could facilitate the diagnosis of individuals with burnout. It recommends taking feelings of guilt into consideration in interventions designed to improve staff burnout.