When the photostimulated cyclization reaction of omega-iodoalkylacrylates was performed in the presence of metal hydride complexes such as sodium cyanoborohydride(NaBH3CN), sodium borohydride(NaBH4) and potassium borohydride (KBH4), the corresponding macrocyclic lactones were produced. The use of NaBH3CN led to the highest yield of lactones.