Catalytic fast pyrolysis (CFP) of cellulose, low-density polyethylene (LDPE), and their mixture (1:1) with ZSM-5 zeolite was investigated to determine the interaction between cellulose and LDPE when they are co-fed in CFP. Results show that CFP of the cellulose and LDPE mixture produced a much higher aromatic carbon yield (47.46%) than CFP of cellulose (37.66%) and LDPE (34.29%) individually. CFP of the mixture also produced a higher aromatic selectivity for more valuable monoaromatics (85.1%) than CFP of cellulose alone (66.7%). Additionally, CFP of the mixture produced much less coke (11.94%) than CFP of cellulose (36.62%). Co-feeding of LDPE with cellulose can thus decrease the rate of catalyst deactivation by coke deposits that occur rapidly in CFP of cellulose. These results indicate that when cellulose and LDPE are co-pyrolyzed with ZSM-5 zeolite, they have a positive synergistic effect that improves aromatic production and decreases coke formation. Co-feeding of LDPE with cellulose thus has a beneficial effect on cellulose conversion in CFP. (c) 2013 Elsevier B.V. All rights reserved.