The pyrogallic method for determining the activity of SOD is studied in the aqueous solution and in the CTAB/n-pentanol/n-octane/water microemulsion. The required generation ran of the substrate O2is obtained in he reverse microemulsion by increasing the apparent pH and dielectric constant. The activity of SOD is finally determined in such a system and a bell-shaped profile is recorded. But subactivity is found only due to the decrease of the substrate concentration and the high pH value