Leucodelphinidin (flavan-diol, I B) under mild conditions of acetylation and another leucodelphinidin (flavan-diol, I A) under more drastic conditions yield the same flav-3-ene-3-ol acetate which produces delphinidin chloride in much better yields than the original diols. Products of reductive acetylation of flavonols agree with flav-3-ene-3-ol acetates in important respects. Reductive acetylation of dihydro-quercetin yields the same product as that of quercetin. Quercetin pentamethyl ether suffers similar reduction under the same conditions. It is therefore concluded that reductive acetylation reduces both the ethylenic and carbonyl groups and is followed by loss of the elements of water.