ABSTRACT This study was aimed to investigate the operational conditions for stabilizing and recycling copper sludge in electronic industry by serially using acid leaching, cementation and ferrite methods. The physical/chemical characteristics of copper sludge were examined, and TCLP (Toxic Characteristics Leaching Process) tests were conducted. Results show that the copper sludge from electronic industry is weakly alkaline and consists of 6-15.8% Cu and 50-75% moisture. The TCLP tests show that copper in the sludge exceeds the regulation standard. Acid leaching tests indicate that the optimal combination of control factor levels yielding more than 99% of copper extraction is: 2.0 N in sulfuric concentration (A3), pH = 1.5 (B3), 90 minutes in treatment time (C3), and 50 oC in treatment temperature (D3). Moreover, the sediment of treated sludge fulfills the standards of the TCLP, and is thus a general industrial waste. Cementation tests indicate that the optimal combination of control factor levels yielding 96.87% of copper recovery and 92% of copper purity is: addition mole ratio of iron element Fe/Cu = 2.0 (A2), pH = 1.0 (B1), agitation speed = 200 rpm (C1), and 50 oC in treatment temperature (D3). Ferrite tests indicate that the optimal combination of control factor levels yielding more than 99% of copper removal is: addition mole ratio of ferrous sulfuric acid Fe2+/Cu = 10.0 (A3), pH = 9.5 (B2), air supply rate = 3.0 L/min (C3), and 80 oC in treatment temperature (D3). The cost analyses indicate that the expenses would be NT $7.45 for the acid leaching-cementation-ferrite process, less expensive than NT $ 8.0 for the solidification process given the same copper sludge. Thus, the proposed method in this study is competitive and feasible. Keywords: Copper sludge, Acid Leaching, Cementation, Ferrite Process, Recycling