Gold deposition on rotating disk electrodes, Bi3+ adsorption on planar Au films and superconformal Au filling of trenches up to 45 mu m deep are examined in Bi3+-containing Na3Au(SO3)(2) electrolytes with pH between 9.5 and 11.5. Higher pH is found to increase the potential-dependent rate of Bi3+ adsorption on planar Au surfaces, shortening the incubation period that precedes active Au deposition on planar surfaces and bottom-up filling in patterned features. Decreased contact angles between the Au seeded sidewalls and bottom-up growth front also suggest improved wetting. The bottom-up filling dynamic in trenches is, however, lost at pH 11.5. The impact of Au concentration, 80 mmol/L versus 160 mmol/L Na3Au(SO3)(2), on bottom-up filling is examined in trenches up to approximate to 210 mu m deep with aspect ratio of depth/width approximate to 30. The microstructures of void-free, bottom-up filled trench arrays used as X-ray diffraction gratings are characterized by scanning electron microscopy (SEM) and Electron Backscatter Diffraction (EBSD), revealing marked spatial variation of the grain size and orientation within the filled features. (C) 2019 The Electrochemical Society.