The processability of decalin, a two-fused ring cycloparaffin, in the absence and presence of USY catalysts of different zeolite crystallite sizes is investigated under actual FCC conditions. Thermal and catalytic cracking experiments using decalin are carried out in the mini-fluidized CREC riser simulator. This novel unit operates under relevant FCC process conditions in terms of partial pressures of decalin, temperatures (450-550 degrees C), contact times (3-7 s), catalyst-decalin mass ratios (5) and using well-fluidized catalysts. Decalin overall conversions ranged between 8-19wt% at low reaction temperatures and 14-27 wt% at high temperatures. It is found that decalin undergoes reactions such as ring opening, protolytic cracking, isomerization, hydrogen transfer and transalkylation. A heterogeneous kinetic model for decalin conversion including thermal effects, adsorption and intrinsic catalytic reaction phenomena is established. Adsorption and kinetic parameters are determined, including the heat of adsorption ( 61 kJ/mol) as well as thermal and primary catalytic intrinsic activation energies, which are in the range of 56-59 kJ/mol and 74-91 kJ/mol, respectively. It is determined that hydrogen transfer reactions are more pronounced and selectively favored against other reactions at lower reaction temperatures, while ring-opening and cracking reactions predominate at higher reaction temperatures. (C) 2009 Elsevier Ltd. All rights reserved.