One of the primary science objectives of the TSS 1 project was that of studying the current-voltage (I-V) characteristics of a highly charged body in the ionosphere. In this paper, using data from experiments of the TSS 1 mission for an event of high satellite charging, we derive points of the I-V characteristics of the TSS satellite. These are then compared with different theoretical models. The comparison shows that the measured currents, for given potentials, are well above the predictions of the Parker and Murphy model. The results obtained appear, in fact, to support a model which computes an enhancement of the collected current due to the rapid motion of the collector across the geomagnetic field. ¿ American Geophysical Union 1995