A recently developed crystallite-scale regeneration model [D. Bhatia, M.P. Harold and V. Balakotaiah, Catalysis Today 151 (2010) 314] is extended and new data are reported that provide insight about cyclic NO x storage and reduction (NSR). The model is based on the concept of NO x spillover from Pt to BaO and diffusion in the barium phase during storage and the reverse process during regeneration. The model is shown to predict the main features of NO x storage, such as the increase in NO x breakthrough time with increased Pt dispersion for fixed Pt loading. The increase in NO x storage with Pt dispersion is a result of (i) an increase in exposed Pt area which leads to a higher intrinsic NO oxidation activity, and (ii) an increase in the interfacial perimeter between Pt and BaO which promotes the rate of NO x spillover. These effects outweigh the known increase in activity with crystallite size. The model is used to simulate the complete lean-rich cycles in order to elucidate the effects of Pt dispersion on various cycle-averaged variables such as NO x /H 2 conversion and N 2 /NH 3 selectivity. The simulations show that a higher stored NO x diffusivity is needed to satisfactorily predict experimental conversion and selectivity trends. This finding suggests the possible involvement of enhanced diffusion, likely of the reductant, during the regeneration. The model is used to study various storage and regeneration timing protocols, such as the use of shorter cycle times to achieve a high cycle-averaged NO x conversion and NH 3 selectivity for low dispersion catalysts. The model also predicts incomplete storage phase utilization both at the crystallite and reactor scales. For example, a reactor containing high Pt dispersion catalyst tends to utilize the storage phase effectively at the crystallite scale but can have significant axial storage non-uniformities, whereas a reactor containing low dispersion Pt catalyst tends to have a more axially uniform storage but poorer local utilization.