Pd-doped chabazite (Pd/CHA) offers unique opportunities to adsorb and desorb NO x in the target temperature range for application as a passive NO x adsorber (PNA). The ability of Pd/CHA to trap NO x emissions at low temperatures (<200 °C) is facilitated by the binding of NO x species at various Pd sites available in the CHA framework. Density functional theory (DFT) simulations are performed to understand Pd speciation in CHA and the interaction of NO with Pd/CHA to explain the mechanisms of NO adsorption, oxidation, and desorption processes. The calculations are used to elucidate the important role of Pd1+ cationic species, anchored at 6MR-3NN, in providing a strong (E b = −272 kJ/mol) NO adsorption site in Pd/CHA. For NO release, the redox transformation of Pd species comes into play and Pd1+ species are suggested to transform into cationic Pd2+, [PdOH]+, or [Pd–O–Pd]2+ species, all of which show significantly reduced NO binding (−116, −153, and −117 kJ/mol, respectively) as compared to Pd1+. This enables NO desorption at the operating temperature of a downstream catalyst for subsequent catalytic reduction.