Photocatalytic ring opening of a-epoxyketones by 2,4,6-triphenypyrylium tetrafluoroborate (TPT) in acetone resulted in the formation of 1, 3-dioxolane as major products through C-O bond cleavage and the formation of alcoholic by-product through C-C bond cleavage. The type and nature of the substituents affect the rate of ring opening.