Catalase, one of the antioxidant enzymes, decomposes hydrogen peroxide into water and oxygen. From the discovery of catalase, several studies have been carried out to reveal its importance in health, food and cosmetics industries etc., and these studies are still ongoing. In this study, catalase enzyme was partially purified from muscle tissue of Dusky spinefoot (Siganus luridus). Purification procedure consisted of homogenate preparation, ammonium sulfate precipitation and dialysis. The enzyme was precipitated in the range of 40-60 % Ammonium Sulfate concentration. The optimum buffer was determined as 200 mM phosphate buffer, optimum pH 8.0 and optimum substrate concentration 24mM for H₂ and O₂, respectively.