The aim of this study was to give insights on the effects of an industrially relevant kilning method, with a focus on lipase inactivation and oat-base production. Storage of non-kilned, dehulled oat kernels in either room temperature or at 37 °C for up to 64 days led to increasing lipase activity with time, despite a decrease in moisture content and water activity, demonstrating the importance of kilning before storage. It was shown that the temperature and relative humidity used during the kilning had a major impact on both protein solubility and lipase inactivation. Steaming with saturated steam at 90 °C for 30 min followed by drying at 100 °C for 30 min was found to be enough to inactivate all lipases but still leave a relatively high protein solubility (42% of the total soluble protein). In the sensory trial, the indication was that kilning was a vital step from a sensory quality perspective, giving a pleasant aroma to the final oat-base product. However, with kilning, the final protein content decreased; thus, these results are important for the development of future oat-base products, where quality, nutritional content, and taste need to be balanced.