The present work focuses on the influence of the surface energy modification of basalt fibers on the fiber wettability at different scales: a single fiber, a strip of fabric and a fibrous preform representative for Liquid Composite Moulding (LCM) processes. To modify the initial surface energy of the basalt fiber, a thermal treatment was used (4h at 400°C). The experimental approach used is as follows: firstly, the surface energy of the modified single fiber was determined, secondly the capillary wicking and the capillary pressure (Pcap) of the fabric were estimated and finally the in-plane unsaturated permeability of the fibrous preform was characterized. The results showed that, after thermal treatment, the surface energy of single basalt fibers is higher, particularly due to the increase of 18% of its polar component. The wicking kinetic was faster and the Pcap increased of 100% in spontaneous impregnation regime. The in-plane unsaturated permeability value of the fibrous preform also rose of 42% in forced regime. In conclusion, the thermal treatment performed improved the wettability between the basalt fiber and the water. Moreover, in the study conditions, the capillary effects proved to be non-negligible on the unsaturated permeability measurement.