Chemistry of superheavy elements / Ru + , Os + , Ti + , Zr + / Ion-molecule reactions / Penning trap Summary. Gas-phase ion chemistry in a Penning trap has been explored for future experiments on the chemical properties of the heaviest elements. The Mainz Cluster Trap, a Penning trap experiment devoted to metal cluster research, has served as a model apparatus for SHIPTRAP which is being installed behind the velocity filter SHIP (Separator for Heavy Ion reaction Products) at the Gesellschaft für Schwerionenforschung (GSI) at Darmstadt. The reactions of stored Ru + and Os + with oxygen have been studied and the reaction products MO + and MO 2 + (M = Ru, Os) have been observed. The corresponding rate constants have been measured and the results are discussed with respect to future studies of similar ion-molecule reactions of the element 108 (hassium) in SHIPTRAP.