A steeping process of barley grains was evaluated regarding lipid oxidation. The steeping process was evaluated with respect to the temperature during the first steep and second steep, and the lactic acid concentration of the steep solutions. The study was conducted using a central composition circumscribed design, and response surface models were estimated with the use of partial least square. The change in the concentration of hexanal was used to monitor the oxidation during processing and subsequent storage at 30°C. In all samples there was hexanal development during processing and the hexanal concentration increased considerably during storage. The results show that it is possible to optimize the process to get a lower oxidation during the subsequent storage. The temperature during the second steep in the hydrothermal process and the level of lactic acid addition were the most important factors. Both of them should be kept low to favor the oxidative stability.