In the present work an attempt has been made to study the effect of catalyst-to-oil ratio (C/O) on the product distribution for the catalytic cracking of mixture of vacuum gas oil (VGO) with guaiacol and acetic acid, which are the representative model compounds of the biomass-derived fast pyrolysis oil. The catalytic cracking of mixture of VGO has been carried out using industrially available FCC equilibrium catalyst (E-CAT) in an advanced cracking evaluation ACE-R FCC unit. The FCC feed, distillates and liquid products are analyzed using Fourier transform infrared spectroscopy, and structurally characterized by H-1, gated decoupled C-13 NMR methods. The average structural parameters like branchiness index, substitution index, average length of alkyl chains, and fraction of aromaticity per molecule are obtained from NMR data. The SIM distillation based product analysis indicated that the presence of guaiacol increased the product selectivity of gasoline fraction; whereas the presence of acetic acid clearly increased the yield of light olefins, CO and CO2. The H-1 and C-13 NMR data indicated that the fraction of aromaticity for both Feed B (vacuum gas oil+ acetic acid) and Feed C (vacuum gas oil + guaiacol) increased, after catalytic cracking, with increase in C/O ratio from 3 to 9. The equilibrium FCC catalyst is able to crack oxygenates presents in pyrolysis oil such as acetic acid and guaiacol. Further the crackability pattern of pyrolysis oxygenates supported by the vibrations of C=O and O-H absorption peaks (of FTIR) and NMR data of liquid product. (C) 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.