The deposition of platinum on copper from a modern commercial electroplating bath (Pt 5Q bath containing 26 mM Pt(NH3)(4)HPO4 + similar to 30 mM sodium phosphate buffer, pH 10.6 at 368 K) has been studied using voltammetry and potential step methods. In addition, polished Cu panels (area 3.4 cm(2)) have been electroplated using both constant potential and constant current conditions; current efficiencies have been determined and scanning electron microscopy has been used to show that the morphology of the platinum layers depends strongly on the plating conditions, particularly the potential at which deposition occurs. It is shown that good quality electroplates can be obtained with high current efficiency but a high rate deposition is more readily achieved using controlled potential.