The usage of lean-burn engines is a promising strategy for improving the fuel economy of vehicles and reducing the emission of greenhouse gas CO₂. Pt-BaO/Al₂O₃ is a lean NO_x trap (LNT) model catalyst that provides a very effective method for NO_x removal in lean-burn gasoline engine exhaust. Recently extensive studies have been made on this model catalyst with focused on understanding of storage and reduction mechanism during lean and rich cycles, and on the influences of conditions such as CO₂ and H₂O. In this presentation we will summarize our understanding of the component role (BaO, Pt, and support Al₂O₃), the condition influence on catalyst performances including O₂ storage capacity during lean cycle, and the reduction ability of Pt during rich cycle. The influence of steam aging temperature on NO_x storage efficiency during lean cycles and on NO_x conversion during rich cycles were also investigated using L/R cyclic reaction. In addition, the status of component and solid interaction between components were characterized (by physisorption, chemisorption, XRD and XPS) and discussed in light of storage and catalytic performances.