We have obtained two-dimensional CCD spectrograms of Comet P/Giacobini-Zinner (1984e) on five occasions between July and October 1985. We extracted spatial emission profiles of H2O+ at 6198 ¿, the strongest ionic line in the visible spectrum. This emission line traces the extent of the ion, or plasma, tail. We placed the spectograph slit approximately along the trajectory of the International Cometary Explorer (ICE) on 11 Sept 1985; the resulting H2O+ profile has full-width-half-maximum of ≈ 5700 km, about three times that of the plasma density profile measured by ICE, and has a full-width-zero intensity of ≈ 30,000 km, very similar to the ICE values. H2O production rates for the comet are derived and compared with those of Comet P/Halley (1982i).