During the exposure process of a wafer scanner, problems occur due to reticle heating. In this project, the consequences of reticle heating in terms of image aberrations are discussed along with how they could be solved with feedback controlled cooling. The problem is defined in terms of a performance index and constraints, which fits the Model Predictive Control (MPC) framework. The principle of MPC is explained and results are compared to the current state of the practice. The results show a significant improvement in performance at the cost of acceptable constraint violations.