Treatment of chlorophyllaor methyl chlorophyllideawith potassium permanganate effected oxidation of the 2-vinyl group without concomitant oxidation of the cyclopentanone ring. One of the products obtained was of especial interest because its visible absorption spectrum was identical with that of a previously known, but chemically uncharacterized, pigment—chlorophylld. The preparation and identification of this oxidation product as 2-desvinyl-2-formyl-chlorophyll-ais given and its probable identity with chlorophylldis discussed in detail.