In this study, the dissolution of spherical copper particles with various sizes was investigated in HNO3 solutions, and a mathematical model was evaluated for the dissolution. From the dissolution runs, it was found that the dissolution rate increased with increasing surface area, stirring speed, temperature and nitric acid concentration and decreasing solid-to-liquid ratio. It was shown that the semi-empirical model for spherical copper particles is: 1 - (1 - X)(1/3) = 7188(A)(1)(S/L)(-1/4WC1/3)-C-1/2 e(-47527/RT) t, where X is conversion fraction, A surface area of particle (cm(2) g(-1)), S/L solid-to-liquid ratio (g cm(-3)), W stirring speed (min(-1)), C acid concentration (% w/w), R constant, Ea activation energy (J mol(-1)), t time (min). It was determined that the dissolution rate is controlled by surface chemical reaction. (C) 2003 Elsevier B.V. All rights reserved.