The influence of the conditions on the rate of Pt electroplating and the quality of the deposited layers are reported for the Pt 5Q bath (26 mM Pt(NH3)(4)HPO4 + approximate to 30 mM sodium phosphate buffer adjusted to pH 10.4 with NaOH). It is confirmed that much higher rates of deposition can be achieved using constant potential control and the resulting deposits are less stressed than those formed by constant current plating. Deposition with high current efficiency is possible at 358 K but again it is more readily achieved at constant potential; the rate of deposition is, however, lower and the plate quality is not as good as observed at 368 K. Finally it is reported that three types of deposit can be identified by scanning electron microscopy (almost featureless, hemispherical growth centres leading to "cauliflower" deposits, and angular crystallites) depending on the cathode potential.