We have developed a new time-dependent kinetic plasma outflow model which uses a kinetic description of the parallel motions of the ion guiding centers, while assuming the electrons are a massless neutralizing fluid (i.e., Boltzmann distributed). The ions, O+ and H+, are followed as individual particles which respond to the gravitational, magnetic mirror and ambipolar electric forces as they move in one dimension along a magnetic flux tube. We show results for a case where the electron temperature in the flux tube is raised from a value near the ion temperature (3000¿ K) to a value of 10,000¿ K. The outflowing hydrogen is little affected by the change, but the barrier to the outflow of oxygen ions is greatly reduced with the result that an enhanced outflow of O+ ions travels up the flux tube. As the oxygen ions adjust to the higher electron temperature the flux of oxygen ions at the lower end of the flux tube increases very rapidly compared to the more gradual increase at the upper end. Also, an enhanced oxygen parallel temperature peak travels up the flux tube, increasing in magnitude as it goes. It travels at a speed significantly higher than the oxygen ion acoustic speed (found with Te=10,000¿ K). ¿ American Geophysical Union 1990