Leaching of an oxidized copper ore containing malachite, as a new approach, was investigated by an organic reagent, citric acid. Sulfuric acid is the most common reagent in the leaching of oxide copper ores, but it has several side effects such as severe adverse impact on the environment. In this investigation, the effects of particle size, acid concentration, leaching time, solid/liquid ratio, temperature, and stirring speed were optimized. According to the experimental results, malachite leaching by citric acid was technically feasible. Optimum leaching conditions were found as follows: the range of particle size, 105-150 μm; acid concentration, 0.2 M; leaching time, 30 min; solid/liquid ratio, 1:20 g/mL; temperature, 40°C; and stirring speed, 200 r/min. Under the optimum conditions, 91.61% of copper was extracted. Leaching of an oxidized copper ore containing malachite, as a new approach, was investigated by an organic reagent, citric acid. Sulfuric acid is the most common reagent in the leaching of oxide copper ores, but it has several side effects such as severe adverse impact on the environment. In this investigation, the effects of particle size, acid concentration, leaching time, solid / liquid ratio, temperature, and stirring speed were optimized. conditions were found as follows: the range of particle size, 105-150 μm; acid concentration, 0.2 M; leaching time, 30 min; solid / liquid ratio, 1:20 g / , 200 r / min. Under the optimum conditions, 91.61% of copper was extracted.