In recent years, experts and academics in the environmental management field have developed an interest in the factors and evaluation techniques that influence corporate environmental investment decisions. However, there are substantial differences between studies employing the most recent evaluation methodologies and those that use indicator systems. To explore the mechanisms that influence corporate environmental investment, this study investigated the determinants of environmental investment through the perspectives of firm, board, chair, and chief executive officer (CEO) characteristics using a machine learning approach. Based on a large-scale data sample from Chinese-listed companies, the results indicated that the extreme gradient boosting (XGBoost) model had an accuracy of up to 97.63%, thus performing the best. Additionally, the model that used SHapley Additive exPlanations (SHAP) to interpret XGBoost showed that a company's sales performance was the most important factor that influenced environmental investment, followed by CEO tenure, board independence, board gender diversity, chair academic experience, and the company's level of internationalization. Furthermore, when examining the sample of heavily polluting enterprises, sales, board gender diversity, CEO tenure, chair academic experience, board independence, and chair-CEO duality, all were found to play crucial roles in predicting environmental investment. Overall, this study aids in evaluating the factors that influence corporate environmental investment decisions and provides policymakers and practitioners with a machine learning approach for use when assessing these factors.

Traditional agency theory views the proper role of the board chair exclusively as providing independent oversight to monitor and control the CEO. Recently, firms have introduced innovations in board leadership that have confounded these theoretical expectations. One notable innovation is the executive board chair, a corporate governance hybrid responsible for both oversight and strategic decision-making, challenging agency theory's prescription that the two activities remain separate. In this study, we argue that an executive board chair position can resolve the trade-off between independent oversight and involvement in strategy and therefore generate a performance advantage. We also predict that, owing to the blurring of lines between the CEO and board chair roles that the executive board chair position creates, the relationship will be stronger the greater the need to monitor and control the CEO but weaker when organizational complexity and board leadership demands are greater. Analysis of S&P 1500 firms from 2003 to 2017 provides general support for our arguments.