A flux of pickup hydrogen ions was detected during the close passage of the Galileo spacecraft past Jupiter's moon Io on December 7, 1995. These protons were detected in a region just prior to and after the spacecraft's traversal of the geometric shadow of the torus plasmas by the solid body of the moon. The presence of a hot ring of protons in velocity space in a plane perpendicular to the local magnetic field is evidence that these protons were produced by a charge exchange of the heavy ions of the torus with the Iogenic atmospheric density of atomic hydrogen. The corresponding proton flux due to this pickup process is characterized by a density of ~30 cm-3 and a bulk flow of 60 km s-1. The corresponding density of atomic hydrogen is estimated as 1¿105 cm-3. Total hydrogen loss from Io is estimated as 3¿1025 H ions s-1 or 50 g s-1. Two candidates for the source of atomic hydrogen from Io's surface are H2S and H2O. ¿ 1999 American Geophysical Union