PURPOSE: To provide a dispersion which enables good electroplating on a nonconductive surface by dispersing effective ratios of carbon black of a specific grain size and surfactant into a liquid dispersion medium.

CONSTITUTION: The dispersion suitable for intensifying metal plating is prepd. from the carbon black particles having the average grain size smaller than about 3.0μm, the effective ratio of the surfactant compatible with the carbon black and water or the liquid dispersion medium, such as 1 to 15C alkyl alcohol. The ratio of the carbon black is specified to a ratio lower by about 4wt.% of the dispersion. This dispersion is applied on the surface of the nonconductive material and the carbon black particles are stuck in a laminar form on the nonconductive surface by separating the liquid dispersion. A conductive metallic layer is electroplated thereon. This dispersion is suitable for a pretreatment for applying the conductive metallic surfaces of copper, etc., on the nonconductive parts of the through-hole walls of printed circuit boards.