The oxidation ofE-5-decene by potassium permanganate in slightly acidic aqueous acetone solutions has been studied. An analysis of the reaction mixture at various time intervals indicates that the ketol, 5-hydroxy-6-decanone, is the initially formed product under these conditions. The other major product, 5,6-decanedione, is formed sequentially from oxidation of the ketol rather than directly from the alkene.