The Royal Projects create valuable knowledge and there is a requirement to structure, store, share and reuse this knowledge effectively. This research aims to analyze, synthesize and formulate structural knowledge of one Royal Project using CommonKADS and ontological-based knowledge management. The Chaipattana Aerator is a patented invention known worldwide for its effectiveness in increasing oxygenation to reduce water pollution and is particularly useful in rural areas where it is utilized by Thailand’s Royal Project Foundation. Three broad ontological categories based on The King of Thailand’s working concepts are proposed, which deal with the principle, essence, and practice concepts of the Chaipattana Aerator Project.