The main purpose of this work is to explain why and how the stock liquidity affects the risk of default of petrochemical and petroleum products companies listed on Tehran Stock Exchange (TSE). The study used experimental data and parametric tests to estimate the relationship between stock liquidity and the risk of default through the roles of stock liquidity in information efficiency and corporate governance. The present research is applied in terms of purpose and is a descriptive-correlative study. All the data required regarding the stock liquidity, price, trading volume and days, stockholder ownerships, etc. were extracted from Rahavard Novin database software. To investigate the relationship between variables, the multivariate regression analysis model using panel least squares (PLS) method was applied in EViews platform. The empirical findings reveal a significant negative relationship between stock liquidity and the risk of default of petrochemical and petroleum product companies listed on TSE. Furthermore, stock liquidity influences the risk of default through pacifying information asymmetry in the stock pricing process and strengthening the corporate governance. These results could provide visible signals based on the realities of the market to improve models assessing and predicting the risk of default, to lead the managers and decision makers of suppliers, customers, partners, and stakeholders to conclude more flexible contracts with petrochemical and petroleum products companies, and to better mitigate business risks.