Specific activities (U mg -1 ) in the dehalogenation of haloalcohols 1,3-dichloro-2-propanol (1f), 2chlorocyclohexanol (2f) and 1,3-dibromo-2-propanol (7g) based on initial reaction rates were determined using the halide release assay . Reactions were performed in duplicate in a total volume of 1 mL containing 10 mM haloalcohol in 25 mM Tris•SO4 buffer pH 7.0 at 30 °C (HheC and its mutants) or 22 °C (HheG and its mutants) using 10-400 µg mL -1 purified enzyme. Sample of 100 µL volume were taken after 30, 60, 180, 270 and 360 s and mixed with 100 μL assay reagent comprising equal volumes of solution I [0.25 M NH4Fe(SO4)2 in 9 M HNO3] and solution II [saturated solution of Hg(SCN)2 in pure ethanol]. Absorbance at 460 nm was measured using a ClarioStar microplate reader. Specific activities were calculated using standard curves for halides Cl -and Br -in the range of 0 to 3.3 mM. Chemical background of negative control reactions without enzyme addition was always subtracted. This assay was also used for the determination of kinetic parameters in the dehalogenation of 1,3-dichloro-2propanol (1f) by HheC mutants. Fir this, the same reaction conditions were used as described above with the substrate concentration ranging from 0.01-20 mM. Resulting kinetic data was fitted using the Michaelis-Menten equation (2) in Origin Pro2021 (see Figure ).