Metal impregnated activated carbon catalysts were prepared by wet impregnation method and their performance for tertiary recycling of waste expanded polystyrene was studied. The conditions were optimized for thermal and catalytic degradation on the overall conversion and liquid products yield. The liquid products were analyzed by GC-MS. The results indicated that desirable and low molecular weight aromatic hydrocarbon were formed with metals impregnated catalysts over AC as compared to thermal degradation and AC support as catalyst. Al/AC was found the best catalyst among the impregnated catalysts with liquid products yield 88.87 wt% (100% total conversion). The yield of toluene; ethylbenzene, styrene monomer and a-methyl styrene were 8.49 wt%, 8.90 wt%. 47.29 wt% and 1.38 wt%, respectively. (C) 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.