Aromatic polyamide particles were prepared by reacting m-phthalyl chloride and 4,4'-diaminodiphenyl ether in a dioxane solution with high water content using a precipitation polymerization method. These nanoscale particles were spherical with a narrow size distribution. The morphologies and characteristic features of the polyamide products obtained depended strongly on the water content of this polymerization system. The characteristic features of the polyamide products were correlated with the amount of 140 (generated during polycondensation) complexed with polyarnide products. Water was essential for the formation of spherical particles and played an important role in determining the polarity of the reaction solution. Further, water removed HCl from this condensation reaction system and played an important role as a reaction accelerator. (c) 2007 Elsevier Ltd. All rights reserved.