The move towards processes in small and microdevices has been increased recently due to the enhanced heat and mass transfer rate of these devices. One particular area of application is liquid-liquid extraction. Hence, the key goal of this study is to miniaturize the implementation of extractive desulfurization of diesel by adopting microchannel technology to overcome the mass transfer limitation of conventional liquid-liquid extraction. The efficiency of the solvent extraction as a result of two-phase flow in an intensified channel highly depends on the flow patterns. In this work, the hydrodynamics of conventional polyethylene glycol 200 (PEG200) and simulated diesel have been investigated intensively by varying several parameters such as junction shape and diameter, channel diameter, and channel saturation at different mixture velocities and solvent volume fraction. To study the effect of solvent properties, experiments were carried out by complexing the polyethylene glycol into a deep eutectic solvent (DES) form by adding a specific amount of tetra butyl ammonium bromide (TBAB) to the PEG200. The main observed patterns were the drop, plug, various states of annular flow, and irregular flow. Those patterns were highly influenced by the channel diameter. Using DES as a liquid solvent resulted in the development of a different form of plug flow known as plug dispersed flow. The measured pressure drop was found to rise with increasing solvent velocity, solvent viscosity, and decreasing channel diameter. The dimensionless analysis showed a reasonable agreement with the experimental work. A new friction factor correlation was generated based on the homogenous pressure drop model using our experimental results. This resulted in improved predictions of the measured pressure drop. The computational fluid dynamics (CFD) was employed using the Volume of Fluid (VOF) model and results were validated with the experimental data. Both experimental and numerical results revealed two-phase flow patterns. The second part involved the utilization of the optimized experimental setup for the extraction of thiophene (Thio) and dibenzothiophene (DBT) from liquid fuel using both solvents. The central composite design (CCD) was employed to visualize the main and interaction effect of different operation factors including channel diameter, channel length, mixing velocity, and volume fraction on the extraction of sulfur compounds. It was found that extraction efficiency fluctuates with respect to mixture velocity. Moreover, the extent of extraction increased with increasing channel length and decreasing channel diameter. Channel cross-sectional area had almost no effect on the EDS efficiency. Finally, a scale-up design based on the numbering-up technique was implemented to check the possibility of implementing the model for high throughput. The proposed scale-up design enhances the mass transfer and the equilibrium was reached in a shorter micro-extractor. Deep removal of sulfur containing components from simulated diesel was achieved in four extraction stages. The percentage of DBT extraction using PEG200 and DES was 98.38 % and 98.66 % respectively. While the deep removal of sulfuric components from real diesel was achieved in six stages. This work gives a clear understanding about the behavior of different solvents to the removal of sulfuric achieve efficient sulfur reduction from liquid fuel in a small scale. It also opens the door for efficient scale-out of microchannels.