tImmobilization of enzymes on solid supports is crucial in enzymatic reactions and catalysis as it allowsreutilization of soluble enzymes and reduces cost. Covalent immobilization of horseradish peroxidise(HRP) on surface-modified mesoporous activated carbon (SMAC) in combination with supercritical car-bon dioxide (scCO2) has been investigated in this study. The supercritical medium achieved higherenzyme loading of 83.5% within 3 h compared to 54% when incubated in aqueous phosphate buffer for30 h. HRP loading in the scCO2environment was consistently higher for different HRP: SMAC ratios. Thesignificant increase in the rate and quantity of HRP immobilization is attributed to the favourable trans-port properties of solutes in scCO2coupled with greater affinity of HRP for the non-polar supercriticalsolvent which enhances the diffusivity of enzymes into the porous matrix. Immobilized HRP retainedenzymatic activity after being reutilized 11 times which indicated that immobilization did not detractfrom HRP’s activity. The immobilized HRP was successfully employed in removing phenol from water viapolymerization of dissolved phenol in the presence of hydrogen peroxide (H2O2). The study shows theadvantage of using a mesoporous substrate as the immobilization platform for enzymes in combinationwith scCO2as the transport medium. It resulted in significant enhancement in the capacity as well as theuptake rate of HRP and resulting in the enhanced phenol removal