We first immobilised the CiHVPO enzyme using the HaloTag TM immobilisation technique as a highly selective and oriented one-step covalent linking method under mild conditions. Having sorted out a reproducible covalent linking of our enzyme to silica particles, we packed the material inside a packed-bed microreactor and evaluated it in continuous flow using an aromatic bromination of pyrroles as model biotransformation. Various runs are presented below to illustrate the application of the setup for continuous flow microreactor sequencing. These measurements were conducted to establish the following points: First, to confirm stable enzyme activity over several days; second, to demonstrate that no enzyme leakage is observed with covalent HaloTag TM immobilisation; and third, to validate stable and reproducible reaction conversion for our model biotransformation. To achieve this, the microreactor was monitored for approx. 22 h, chromatograms were measured every 15 min (Fig. ), and a constant reactant stream was applied. Two consecutive runs of the same microreactor were then carried out as recycling experiments, with the reactor washed with buffer overnight after each run (Fig. ) and the fraction of the product 2 signal visualised (for relative evaluation, only one brominated product isotope considered). These long-term monitoring runs of the immobilised enzyme successfully demonstrated good operational stability with only a slight drop in biocatalytic activity over time. Interestingly, some enzyme activity was regained during the overnight washing step. To confirm the selective immobilisation only via the HaloTag TM , measurements were conducted with particles without chloroalkane linker. In this case, the enzyme was presumably attached to the ProntoSIL particles through non-covalent interactions during the enzyme immobilisation process. These interactions, however, proved insufficient to withstand the flow conditions, resulting in a significant loss of activity due to clearance of the enzyme from the reactor over time (Fig. ). Similarly, blank ProntoSil particles with a linker but without enzyme addition showed no conversion at all. Additional information and further runs at different reaction conditions can be found in the ESI at section S5.1.