Introduction: Nurse’s competency plays an important role in achieving health system objectives. One of the problems in health care system in various countries is the level of nurses' competencies. The aim of this study was to determine clinical competency and psychological empowerment of nurses and their correlation with demographic characteristics.

Materials and Methods: In this descriptive-correlational study, 170 subjects were selected through simple random sampling method among the nurses of social security hospitals in Tehran. Data was gathered by the questionnaire with three parts: personal-social characteristics, “Clinical Competency Questionnaire" and "Psychological Empowerment Spreitzer". Validity and reliability were confirmed in previous studies. Data were analyzed by SPSS/13.

Findings: The highest mean score in clinical competency was seen in managerial capabilities dimension (44.41±5.8) and the lowest mean score also was seen in diagnostic procedures dimension (13.94±1.84). The highest mean score in psychological empowerment was in competency dimension (9.4±1.38) and the lowest mean score also was in independence dimension (8.37±1.72). In addition, there was a significant correlation between the number of staff in ward, educational status of nurses and some dimensions of clinical competency and psychological empowerment and also between the working experience in current ward and some dimensions of clinical empowerment and clinical work experience and some psychological empowerment dimensions (P<0.05).