This article presents the results of a study of the hydrophilic properties of VMPS-10 84x4 glass filaments and SYT-49S 12K carbon tows. It has been found that the contact angle of glass and carbon fibers, which decreases after ion-plasma treatment, returns to its original values within 8 days. The capillarity values of both types of fibers increase irreversibly, but for carbon fibers, we observe a more significant change in this parameter. In the course of studying the microstructure of the surface of filler fibers before and after processing, it was found that all samples were uniformly covered with a film of an active lubricant with a microdispersed structure; however, for glass fibers, the size of the sizing particles increased during processing, and for carbon fibers, it decreased. In addition, thermophysical studies of the used reinforcing fillers were carried out, and it was found that during the ion-plasma modification, the erosion of the sizing film occurred.