The principal ion in the ionosphere of Triton is N+. Energetic electrons of magnetospheric origin are the primary source of ionization, with a smaller contribution due to photoionization. To explain the topside plasma scale height, we postulate that N+ ions escape from Triton. The loss rate is 3.4¿107 cm-2 s-1 or 7.9¿1024 ions s-1. Dissociative recombination of N+2 produces neutral exothermic fragments that can escape from Triton. The rate is estimated to be 8.6¿106 N cm-2 s-1 sor 2.0¿1024 atoms s-1. Implications for the magnetosphere of Neptune and Triton's evolution are discussed. ¿ The American Geophysical Union 1990