Unsteady-state operation of a trickle-bed reactor (TBR) was investigated using a multi-step exothermic reaction, hydrogenation of dicylcopentadiene (DCPD) in the presence of Pd/Al2O3 catalyst. The influences of five operation strategies on the reactor performance were symmetrically studied and compared with the steady-state operation, including ON-OFF and PEAK-BASE modulations of the liquid flow rate or concentrations, and a novel hybrid modulation of liquid flow rate and concentration. Attempts were also made to develop an unsteady-state operated TBR model based on a plug-flow model incorporating fluid flowing behaviors, three-zone partial wetting catalyst, vapor-liquid phase equilibrium and enthalpy balance, to predict the overall performance under unsteady-state operations. Compared with the experimental observations, it is indicated that the developed model is generally reliable to predict performance enhancement for different modulation strategies. (C) 2008 Elsevier Ltd. All rights reserved.