A process for producing a stampable reinforced composite semi-finished product comprising one or more plastics and chopped fibers or continuous filaments, the softening temperature of which is above the highest of the softening temperatures of the materials, comprises the steps of: depositing the fibers or filaments, especially by gravity, onto a conveyor; sprinkling particles of a powder of the plastics onto the fibers or the filaments, in a proportion of between 5% and 90% of the total weight; blending the particles with the fibers or the filaments; and heating the blend to a temperature above the softening temperatures of the materials. The blending step includes subjecting the blend to at least one electric field approximately perpendicular to the direction of advance of the conveyor.