K, Zn, Cs and La ion-exchanged Y zeolites were prepared and used as photocatalysts for the isomerization of norbomadiene. The prepared catalysts were characterized by EDS, XRD, Al-27- and Si-29-NMR, UV-vis and IR. The La-exchanged sample showed the highest degree of exchange, but accompanied with some dealumination. La-exchange generated both B-acid and L-acid sites, whereas other metals produced only L-acid sites. For the photocatalytic isomerization reaction, the activity order was LaY > CsY > ZnY > KY. The heavy atom effect and B-acidity are expected to play important roles in the reaction.