Mn-Na2WO4/SiO2 is one of the very few catalysts for the oxidative coupling of methane, whose stability over extended times on stream has been reported by different research groups. The high stability turned Mn-Na2WO4/SiO2 into an object of research, despite the rather complex composition and structure. The nature of the active site or the active phase is unclear, in spite of the research on this catalytic system. This manuscript tries to critically summarize the literature on this system and to discuss the available information about the relationship of structure and activity. (C) 2012 Elsevier B.V. All rights reserved.