Bimetallic three-way catalyst devices include a support body, one or more Rh bulk deposits disposed on the support body, and a plurality of Pt atomic clusters disposed on the surface of each of the Rh bulk deposits. Substantially no Pt is deposited on the support body. At least 85% by weight of the Pt atomic clusters comprise up to 10 atoms and the maximum Pt atomic cluster size is 200 Pt atoms. The combined loading of Rh and Pt can be less than 1.5% by weight relative to the weight of the support body. The molar ratio of Rh in a bulk Rh deposit to Pt disposed on the surface of that deposit is at least 5:1.