The efficiency and selectivity of chemical reactions are influenced by the mixing characteristics of the reactor. Existing models often assume homogeneous mixing on micro scale to calculate the reaction yield. However, neglecting the local hydrodynamic phenomena causes a discrepancy between model calculation and experimental data especially considering mass transfer limited reactions. In two-phase flows different mass transfer phenomena have to be considered: the diffusion in the gas-liquid boundary layer and diffusion in the Batchelor layer. The aim of the paper is to describe the mass transfer affecting mechanisms in multi-phase flows and to discuss the first results of the investigation of local mass transfer phenomena in a two phase flow driven jet-zone loop reactor.