The influence of periodic operation on trickle-bed reactor (TBR) hydrodynamics and gas-liquid mass transfer was investigated. Two-phase pressure drop, dynamic liquid hold-up and gas-liquid mass transfer coefficient (k(L)a) were determined at various liquid flow rates and for different modes of liquid flow variation (increasing and decreasing liquid flow rate). The results reveal the considerable influence of type of liquid flow rate modulation on k(L)a values (deviations of up to 80% in k(L)a). Simulation studies on gas-limited reaction in a periodically operated TBR indicate that an enhancement in conversion of about 14% can be expected from an appropriate selection of the operating mode, thus clearly demonstrating the quantitative process intensification feasible through increased gas-liquid mass transfer. (C) 2010 Elsevier B.V. All rights reserved.