Within the framework of process intensification there is a growing demand for novel reactor technologies For the improvement of halogenation of ketones a let-zone loop reactor (JZR) is used, which leads to an enormous increase in yield and selectivity compared to stirred vessels (Kutschera et al., 2008) This JZR is a special let loop reactor with high specific mass transfer performance and good macromixing behaviour It is obvious that there is direct relation between the reaction and the hydrodynamics in the reactor Despite several aspects of hydrodynamics in let loop reactors have been investigated, the essential flow characteristics behind a two-component Jet are not sufficiently understood In these investigations, the flow field in the Jet zone of the JZR was analysed by 2D particle image velocimetry (PIV) and the kinetic energy dissipation rate E was determined from the spatial gradients of the fluctuating velocity