The barriers and heats of reaction for the conversion of benzene cation to naphthalene cation by acetylene additions using the B3LYP/6-31G* approach are reported. The barrierless path we previously reported, using the B3LYP/4-31G approach. is shown to be incorrect. New paths for the ring formation are shown to have low barriers. (C) 2002 Published by Elsevier Science B.V.