A lean NOx trap composition for the treatment of exhaust gas emissions, such as the oxidation of unburned hydrocarbons (HC), and carbon monoxide (CO), and the trapping and reduction of nitrogen oxides (NOx) is disclosed. The lean NOx trap composition can have a washcoat layer on a carrier substrate including a first support material comprising greater than 50% by weight of a reducible metal oxide; 10 to 30% by weight of alkaline earth metal supported on a second support material comprising a refractory metal oxide and 50% or less by weight of a reducible metal oxide and; and a platinum group metal component supported on at least one of the first support material and/or the second support material. A portion of the first support material may further include 0.5% to 10% by weight of an alkaline earth metal.