A series of Cu-beta zeolites with different Cu contents have been prepared. Their activity for selective catalytic reduction (SCR) of NO with C3H8 has been studied and compared with that of Cu-ZSM5 zeolites. Cu-beta samples are stable SCR catalysts giving activities as high as those of Cu-ZSM5 zeolites. Their behaviour toward reaction temperature and oxygen content is practically the same as that of Cu-ZSM5. Similar results were achieved when the adsorption of NO over the zeolites was followed by i.r. spectroscopy.