A kinematically complete experiment for transfer ionization in slow He $^{2+}$ - He collisions L. Schmidt, V.Mergel, M. Achler, L.Spielberger, O. Jagutzki, R. Dörner, H. Schmidt-Böcking Institut für Kernphysik, J.W. Goethe-Universität Frankfurt, Germany Using COLTRIMS, we measured the transfer ionization He $^{2+}$ + He -> He$^+$ + He $^{2+}$ + e$^-$ for projectile velocities between 0.5 and 1 a.u. and obtained the 3-dimensional momentum distribution for all particles in coincidence. Different cuts and projections in the phase space of the final- state show structures which can not be understood at this time.