1.0 wt.% Pt supported catalysts were prepared by incipient wetness impregnation of Mg–Al supports obtained by thermal decomposition of commercial hydrotalcite-type (HT) precursors with different Mg/Al atomic ratios (1.3, 2.0 and 3.0, respectively) and investigated in the storage–reduction of NO x (NSR). These catalysts showed improved performances in comparison to a Toyota-type Pt–Ba/Al 2O 3 catalyst at temperatures ≤ 250 °C. This behaviour can be attributed to the formation of well-dispersed cubic Mg(Al)O mixed oxides, which showed good NO x -storage properties, significantly better than those of the stoichiometric spinel MgAl 2O 4. Both the catalytic activity and the stability after a hydrothermal treatment of Pt/HT catalysts increased by increasing the Mg/Al atomic ratio, while the analogous Pt/MgO catalyst deactivated almost completely, evidencing the key role of the HT precursor.