In the present work preliminary results are given of an experimental programme on flame spreading over the surface of PMMA rods in NgO2 mixtures under microgravity conditions. Results were obtained in the NASA KC-135 aircraft laboratory. Six experiments were carried out in March of this year and 36 more experiments will be conducted in March 1987. These preliminary experiments allowed to determine the flame spreading velocities for three different mixture compositions, showing that they were smaller but of the same order of magnitude than downwards spreading velocities at one g and for the same mixture condition