Postgraduate education is said to support the development of nurses' professional competence and confidence, essential to the delivery of safe and effective care. However, there is a shortness of empirical evidence to demonstrate an increase to nurses' self-reported confidence and competence on completion of critical care postgraduate certificate-level education.To explore the impact of a critical care postgraduate certificate course on nurses' self-reported competence and confidence. To explore the psychometric properties and performance of the Critical Care Competence and Confidence Questionnaire.A quasi-experimental pre/post-test design.A total population sample of nurses completing a critical care postgraduate certificate course at an Australian University.The Critical Care Competence and Confidence Questionnaire was developed for this study to measure nurses' self-reported competence and confidence at baseline and follow up. Descriptive and inferential statistics were used to explore sample characteristics and changes between baseline and follow-up. Reliability of the questionnaire was explored using Cronbach's Alpha and item-total correlations.There was a statistically significant increase in competence and confidence between baseline and follow-up across all questionnaire domains. Satisfactory reliability estimates were found for the questionnaire.Completion of a critical care postgraduate certificate course significantly increased nurses' perceived competence and confidence. The Critical Care Competence and Confidence Questionnaire was found to be psychometrically sound for measuring nurses' self-reported competence and confidence.