A new approach to reactor model building for two-phase absorption processes is developed by considering simultaneously mass and heat transfer phenomena, and chemical reaction mechanism and kinetics. In particular, the interaction of mass and heat transfer with chemical reaction over the reactor design is considered to improve the accuracy of the simulation results. A novel methodology is applied to identify suitable reaction mechanisms and kinetics based on limited experimental data. This methodology allows the engineer to develop feasible reaction mechanisms in a systematic approach. Importantly, the required scope for any further lab experiments is identified, especially when the modeling needs further clarification for the reaction kinetics or mechanisms. In this way, a more robust reactor design can be achieved by making full use of experimental information, saving unnecessary laboratory and pilot plant experiments. For a case study, chlorine absorption to oleic acid is applied to the modeling of a laminar jet absorber.