Reviews of aqueous processing in JOM have traditionally focused on hydrometa llurgical process routes. This article, however, addresses the application of aqueous processing in materials engineeri ng and presents some promi sing developments that employ aqueous-based routes for th e manufacture of high-tech componen ts and specialty products. Such applications include producing metallic and ceramic powders; etching; surface modification by electroplating and electro less plating; manufacturing jewelry and intrica te componen ts by elec troforming; and producing advanced cerami cs, composites, and nanophase materi als by sol-gel and biomimetic processing.18