The theory for a spherical collisionless planetary corona is extended to include charge exchange collisions between H+ and H, which are assumed to constitute intermingled gases with different kinettic temperatures. The treatment is based on the conventional concept of a critical level (or exobase), above which the only collisions considered in the Boltzmann equation are those that resonantly exchange charge. Satellite orbits are not included. Although the geometry treated is an oversimplification for a real planet, numerical examples are given for an idealized earth and Venus. For earth an ion temperature of 4 times the neutral temperature, an ion density at the exobase of 1.4¿104 cm-3, and a plasmapause at 1.5 RE will raise the escape flux of R by a factor of 6. The total H above the exobase is changed by less than 1%. For Venus the conditions are examined that would account for the peculiar H distribution observed from Mariner 5. The plasma conditions required are not obviously outrageous by terrestrial standards, but the Mariner 5 ionosphere measurements did not show a high plasmapause at, say, 1.25 or 1.5 planetary radii, a fact that might argue against a charge exchange model.