Copper powder was treated at room temperature and at 80 degrees C by immersing in deionized (DI) water, in DI water with hydrogen bubbling, and in aqueous media containing various concentrations of Cu(NO3)(2). Negligible growth occurred at room temperature in DI water with hydrogen bubbling, consistent with negligible copper ions in solution. In all other cases, particle growth occurred to varying degrees. In general, the higher the copper ion concentration, the faster the growth kinetics. Experiments were also conducted in DI water, DI water with hydrogen bubbling, and in 0.01 M Cu(NO3)(2) solution for up to 144 h. The average particle size exhibited a linear dependence on time. The mechanism of growth involves a coupled transport of copper ions through the aqueous medium and an electron transport through the direct particle-to-particle contact. This growth may be referred to as the electrochemical Ostwald ripening and electrochemical agglomeration.