Chemical recycling of expanded polystyrene foams is tertiary recycling and considered an alternative for low-cost waste treatment because of it is simple and environmentally friendly process. Chemical recycling of expanded polystyrene is described by three routes: (1) solvent-based polystyrene dissolution (2) polystyrene structural modification and (3) polystyrene depolymerization. These strategies represent a useful option to generate new materials such as: fiber, membrane, cationic exchanger resin (flocculant materials), polyelectrolyte, and fuel cell membranes and they was explored to obtain high value aromatic products: styrene (monomers and oligomers), toluene, propenyl benzene, ethyl benzene, benzoic acid and other aromatic compounds. This chapter presented and discussed current trends, advances and alternatives for chemical recycling of polystyrene wastes.