Ultrasonic spray pyrolysis has been used to obtain fine spherical powders of WPA bronzes from a 29-tungstenphosphoric acid (WPA-29) feed solution. The average grain size of the obtained powder particles is ca. 1000 nm; these consist of subparticles in the 30-80 run range. The experimentally determined average WPA bronze particle size values are compared with theoretically calculated ones; fairly good agreement between them is found. It is also shown that the average grain size and grain size distribution of the structure and substructure of the obtained powder are predictable. (c) 2005 Elsevier B.V. All rights reserved.