Through-hole plating capability was examined for process electrolytes made up with various organic additives. Tafel plots were obtained from cyclic voltammetry using the rotating-disc technique. The levelling capability of the electrolytes was obtained from coulometry and in situ microgravimetry in combination with optical microscopy, the throwing power for through-hole plating from the thickness ratio center of hole-plane surface outside the hole. It was shown that a high throwing power correlates with a low levelling capability. The results shed some light on the inhibiting character of the process electrolytes used.