Catalase-loaded solid lipid nanoparticles (SLNs) were prepared by the double emulsion method (w/o/w) and solvent evaporation techniques, using acetone/methylene chloride (1:1) as an organic solvent, lecithin and triglyceride as oil phase and Poloxmer 188 as a surfactant. The optimized SLN was prepared by lecithin: triglyceride ratio (5%), 20-second + 30-second sonication, and 2% Poloxmer 188. The mean particle size of SLN was 296.0 +/- 7.0 nm, polydispersity index range and zeta potential were 0.322-0.354 and -36.4 +/- 0.6, respectively, and the encapsulation efficiency reached its maximum of 77.9 +/- 1.56. Catalase distributed between the solid lipid and inner aqueous phase and gradually released from Poloxmer coated SLNs up to 20% within 20 h. Catalase-loaded SLN remained at 30% of H(2)O(2)-degrading activity after being incubated with Proteinase K for 24 h, while free catalase lost activity within 1 h.