A convenient strategy to intensify the liquid-liquid mass transfer performance in a capillary microreactor system was developed by narrowing the inlet channel of T-micromixer or adding baffles into the capillary. Various geometrical parameters such as the inlet mode and diameter of the modified T-micromixer, the number of baffles and interval distance between baffles in the modified capillary were investigated to elaborate the mass transfer intensification mechanism. The liquid-liquid two-phase flow patterns in new capillary microreactors were captured by a high-speed camera. Moreover, pressure drops and specific energy dissipation of these modified microreactor systems were studied and a new parameter indicating the ratio of the mass transfer coefficient to the energy dissipation was proposed. This work highlights the modified capillary microreactor systems with embedding baffle units for achieving high mass transfer rates with its advantages over other types of reactors or microreactors considering specific energy dissipation and effective energy utilization efficiency. (c) 2018 American Institute of Chemical Engineers AIChE J, 65: 334-346, 2019