A sequential process that composed of thermal treatments, shredding, calcination, leaching, and precipitation steps was proposed to recycle spent lithium ion batteries (LIB). Electrode materials from LIB was shredded and thermally treated at 500 ℃ in air. The cathodic active material, LiCoO2 powder from the eletrode materials, was concentrated by calcination at 800 ℃ for 2 h. At 2 M sulfuric acid and 75 ℃, in the absence of a reducing agent, the extraction of cobalt was less than 40% while the lithium recovery reached almost 100%. When excess of 20 vol% of hydrogen peroxide was added as a reductant, the extraction of both metals exceeded 95%. The extraction of both Co and Li increased by increasing H2SO4 concentration, temperature, and amount of hydrogen peroxide, but it decreased with the pulp density. With a neutralization step, where LiOH was added to the leach liquor, at pH 7, the cobalt recovery improved to more than 95%.