Disclosed is a process for opening naphthenic rings of naphthenic ring-containing compounds, and catalysts which can be used in that process. The naphthene ring opening catalyst is a polymetallic catalyst comprising Group VIII metals. In a preferred embodiment the naphthene ring opening catalyst comprises Ir in combination with a Group VIII metal selected from at least one of Pt, Rh, and Ru, in an amount effective for opening a naphthene ring-containing compound at a tertiary carbon site.