Peroxidase from white turnip (Brassica rapa) was immobilized as cross-linked enzyme aggregate (CLEA) via solvent precipitation and glutaraldehyde cross-linking. The nature of the precipitation solvent, enzyme and glutaraldehyde concentrations affected the formation and the activity of the enzyme aggregate. The aggregates resulting from cross-linking with glutaraldehyde produced insoluble catalytically active cross-linked enzyme aggregates. Acetone was selected as the more efficient solvent, giving the highest activity recovery (28%) and aggregation yield (78%). Immobilization was conducted for 3 h under agitation at 4 1C. Optimal conditions were determined as 2% (v/v) glutaraldehyde and 9:1 (v/v) enzyme to glutaraldehyde ratio. The highest activity recovery and aggregation yield were 42.5% and 82% respectively. CLEAs with enhanced thermal and acidic condition stabilities were formed when compared to the free enzyme. The cross-linked enzyme aggregates exhibited optimal pH and temperature in the range 6–7 1C and 40 1C, respectively. CLEAs of Brassica rapa peroxidase exhibited good stability in nonpolar organic solvents and they could be stored in pH 7 buffer with no activity loss at 4 1C for more than three months