The reactions of cyclopropane in helium and hydrogen were investigated over two different loadings (10.7 and 6.0 wt%) of ion-exchanged Ni/NaX zeolites. The effects of reduction temperatures and hydrogen treatment times on catalytic activity and acidity were studied. Apparent activation energies ranged from 35.5 to 95.4 kJ/mol for isomerization reactions over two loadings of Ni/NaX zeolite reduced under different conditions. Rates of isomerization, hydrogenation, and hydrogenolysis are also reported. Deactivation and regeneration of catalysts are discussed. Particle sizes of 8.9 and 17.3 nm were observed in highly reduced Ni zeolites. Sintering of Ni was observed on the surfaces of the zeolite crystallites. Temperature programmed reduction studies show that stoichiometric amounts of H-2 were used to completely reduce all Ni in the samples. Infrared analysis of chemisorbed pyridine on these materials show that higher loadings of Ni result in higher initial acidities. Increased amounts of reduced Ni significantly increase the number of Bronsted sites on the surface of the catalyst. Electron paramagnetic resonance revealed that Ni+ was present in low loaded Ni/NaX samples upon reduction at low temperatures (350-degrees-C), while higher reduction temperatures (450-degrees-C) resulted in a broad EPR signal corresponding to Ni0 only. Na vapor deposition experiments, designed to selectively poison Bronsted sites on the catalyst, reveal that Ni+ ions are active in cyclopropane isomerization reactions at high temperatures. 1994 Academic Press. Inc.