We report isotope-selective loading and trapping of doubly ionized ytterbium into an rf quadrupole trap. Isotopically pure clouds of
174Yb+ ions were first loaded into the rf trap via a multistage photoionization process. The Yb
2+ ions were then produced by electron impact ionization of the trapped Yb
+ ions. The Yb
2+ ions were subsequently detected by rf excitation of their secular motion in the trap, which led to sympathetic heating and changes in the fluorescence of the laser-cooled Yb
+ ions. The presence of doubly charged Yb ions was further verified by the appearance of a dark band in the center of Yb
+ ion cloud after electron impact ionization. We discuss the possible formation of Yb
2+H and similar compounds and the schemes for the direct optical detection of the Yb
2+ ions.