The invention is targeted mainly at a process for the preparation of a semifinished product comprising a PAEK-based resin and reinforcing fibers, comprising the stages of:



a. preparation of a dispersion comprising a PAEK-based resin in the pulverulent form dispersed in an aqueous phase comprising a surfactant;
b. bringing the reinforcing fibers into contact with said aqueous dispersion;
c. drying the fibers impregnated with dispersion; and
d. heating the impregnated fibers to a temperature sufficient for the melting of the resin, so as to form a semifinished product,

characterized in that the surfactant is a thermally stable surfactant. It is furthermore targeted at the dispersion of use in said process. Finally, it is targeted at the semifinished products capable of being obtained and also at their use in the manufacture of composite materials.