This paper investigates the impact of CEO optimism level on the cost of debt in Real Estate Investment Trusts (REITs) in the U.S. market. CEO optimism is measured by following Malmendier and Tate's (2005) approach using the average moneyness of vested options held by the CEO. Then using the spread between the yield of the bond at the end of every year following origination and the treasury rate with the same or closest time to maturity, the cost of debt is calculated. After controlling for other variables including fixed effects, firm and CEO characteristics, the results show that high(low) CEO optimism level conveys a markup of 31(13) basis points on average on the cost of debt encountered by REITs.