A four-member ring hypervalent iodine radical has been detected in the laser flash photolysis of 1,3-diiodo-1,3-diphenylpropane. This species absorbs at 320 nn, has a lifetime of similar to 9.5 mu s in cyclohexane, and is not quenchable by oxygen. Excitation of this radical by means of laser-drop photolysis results the formation of trans-1,2-diphenylcyclopropane through concerted iodine extrusion.