Lithium ion batteries (LIBs) are used for products that require high capacity and voltage, such as hybrid vehicles and electric vehicles. With increasing worldwide demand and the localized distribution of sources for the Li and Co that are critical for manufacture of LIBs, it is important to separate and recover these materials from used batteries. In this study, the recovery process of Li and Co was investigated by using the undersize products after a series of roasting, crushing and classification of LIBs. Li was selectively leached from the undersize products with water and recovered as Li2CO3 by applying solvent extraction and crystallization-stripping operations. Co was selectively leached with dilute nitric acid from the leaching residue of the previous step and was recovered asoxalates. The proposed process is very simple, consisting of selective leaching and crystallization-stripping for Li and oxalate precipita tion for Co.