Acetone fractionated peroxidase from crude extract of Brassica oleracea leaves (Cabbage) was purified in three steps on chromatographic columns, using Sp-Sepharose, DEAE-Sepharose and Con A-Sepharose. The specific activity of purified main isoenzyme (BOC-POD) is 1887 u/mg protein with RZ: 3.1, which is 172 times more than the RZ of crude extract with 4.3% recovery. The molecular weight of BOC-POD is about 45,000 Dalton. Maximum pH, thermal activity and stability of this purified enzyme are also determined. Km of this isoenzyme was measured by Linewearver-Burk curve for O-dianisidine towards H2O2. This purified enzyme could be used in manufacturing diagnostic kits.