More than 200,000 tons of portable batteries and accumulators are placed on the market annually in the EU countries and more than 20 wt. % of them are lithium ones. In addition to lithium, they contain metals such as cobalt, nickel, manganese, copper aluminum and others. High share of lithium battery and a limited lifespan results to a large quantities of waste. Pyrometallurgical recycling methods, which are currently more widely used, have a lower selectivity and consist only in the recovery of selected metals. The remaining substances are concentrated in slag, which is deposited in landfills. Lithium slag composition and leaching behavior of lithium and cobalt in Sulfuric acid was studied in this paper. The leaching was carried out in 0.1, 0.5, 1 and 2M H 2 SO 4 with and without 30 ml of H 2 O 2 at temperatures of 20, 40, 60 and 80°C. All slag samples were leached for 90 minutes with constant stirring of 300rpm at liquid to solid ratio of 50. The obtained results showed that 66.85% of Co and 99% of Li was leached at 1M H 2 SO 4 with addition of H 2 O 2 at temperature of 80°C.