the main purpose of this study is to investigate the effect of CEO power on tax avoidance by considering the moderating role of audit committee quality in companies listed on the Tehran Stock Exchange. In this study, we calculate the CEO power index using CEO's membership in the board, long-term tenure, share ownership and composition of the board. Also, the audit committee quality was measured by indicators of size, financial expertise, independence and gender diversity. The statistical sample of the research includes 191 member companies of Tehran Stock Exchange during the years 2013 to 2020. The results suggest that the CEO power has a negative and significant effect on tax avoidance. In other words, tax avoidance is lower in firms with powerful CEOs than in other firms. the results of the study indicate that the quality of the audit committee does not have a significant effect on the relationship between CEO power and tax avoidance. For the first time, this study provides evidence related to CEO power and tax avoidance in corporate markets and contributes to expanding the literature in this field. In addition, the evidence of this study is suitable for observers and policy makers in Iran and gives them a positive sign regarding recommending or requiring an audit committee in the board of directors.