(NH4)(2)RuCl6 is one of the most important precursors for the preparation of Ru powder with high-purity requirement. In this study, high-purity (>99.999 wt%) micro-spherical (from 23 to 10.4 mu m) (NH4)(2)RuCl6 particles with controllable surface were synthesized by chemical separation method combined with spray drying process. After the chemical separation, high-purity (NH4)(2)RuCl6 precipitation was achieved, while the morphology, size and surface of (NH4)(2)RuCl6 particles were controlled by the spray drying process. The detailed influencing mechanisms of spray drying process, including gas/liquid rate, drying temperature and solution concentration, were investigated. Both gas/liquid rate and drying temperature influence the morphology and size of spray dried particles, while solution concentration is directly proportional to size of spray dried particles. It should be noted that the powder technology in this study could be applied to synthesize other high-purity spherical particles. (C) 2017 Elsevier B.V. All rights reserved.