Lithium recycling from spent LIBs along the COOL‐process produces a Li‐free metal rich black mass, which still contains the entire fraction of valuable metal such as Co, Ni, and Mn. A recycling process was developed, which allows for mobilizing these metals. The first process stage is the selective leaching of Li via COOL‐process. Subsequently, two inorganic (H2SO4 and HCl) and two organics acids (citric and gluconic acid) were tested for mobilizing the metals from the solid residue. To optimize this process stage, acid concentration as well as addition of H2O2 as a reduction reagent were investigated. The optimal conditions to dissolve valuable metals such as Co, Cu, Fe, Mn, and Ni was identified as 2 N H2SO4 and 2 vol % H2O2.