A catalyst for opening naphthenic rings has been developed. The catalyst comprises ruthenium and platinum as the active catalytic metals and a modifier with cerium being a preferred modifier. At least 50% of the platinum and ruthenium components are present as particles wherein more ruthenium is present on the surface of the particles than in the center. All of these components are dispersed on a metal oxide support such as aluminas. A ring opening process using the catalyst is also described.