Abstract Background: The following study presents a colorimetric method for the assessment of serum catalase activity which yields precise, accurate, reproducible results and is simplified so that clinical pathology laboratories may achieve this determination without the need for special techniques. Methods: In this method, dichromate in acetic acid is reduced to chromic acetate when heated in the presence of undecomposed hydrogen peroxide (H 2 O 2 ), with the formation of perchromic acid as an unstable intermediate. Hydrogen peroxide concentration is directly proportional to the concentration of chromic acetate that produced from the reaction. The chromic acetate produced is measured calorimetrically at 570 nm. Findings: The imprecision of the method was calculated by measuring the coefficient of variation, which equals to 3.4% within run and 5.9% between run. The catalase assay performed using the kinetic method yielded a good correlation (r = 0.9771). Applications: The present method characterizes by adding a correction factor to eliminate the interference that arises from the presence of sugars, amino acids, proteins and vitamins in serum. New Method for Assessment of Serum Catalase Activity Mahmoud H. Hadwan* Chemistry Department, College of Science, University of Babylon, Hilla city, Babylon Governorate, P.O. 51002, Iraq; mahmoudhadwan@gmail.com Keywords: Catalase Activity, Clinical Pathology, New Method Serum, Spectrophotometry 1. Introduction he rapid development of clinical pathology form of payments to all branches of enzymology, including ana- lytical assessment 1,2 . Rapid methods for the estimation of catalase activities in the active ield of applied biochemis- try are increasing due to the broad importance of catalase in clinical pathology. Serum catalase (EC 1.11.1.6) activity is increased in acute pancreatitis for a considerably longer time than the serum amylase activity and is also recorded to be raised in chronic pancreatitis 3 . Although this has been recognized for several decades, serum catalase activ- ity has achieved little attractiveness because of the lack of simple and reliable methods for its assessment 4 . Catalase can be assessed by determining the rate of decomposition of H 2 O 2 (at 240 nm) 5 . here are practi- cal diiculties with this method, which belonging to using very high and un-physiological levels of substrate (5-50 mM) for attaining acceptable initial absorbance (the absorbance of H 2 O 2 at 240 nm is only 39.4 M -1 cm -1 ) 6 . hese high levels of H 2 O 2 lead to rapidly but vari- able auto-inactivation of catalase by modiication of the active enzyme - H 2 O 2 complex I to the inactive complex II. Moreover, many cellular components such as proteins absorb strongly at 240 nm so that low activities of cata- lase oten have to be measured by the continuous method against an elevated background absorbance 5 . Other documented methods for determining catalase activity involve titrimetric determination of hydrogen peroxide, determination of oxygen production by oxygen electrode, immune-precipitation and gasometric determination of hydrogen peroxide 8,9 . hese methods are tedious and not suitable for clinical use. Modern assays of catalase include three methods. he irst depends on the enzymatic consumption of hydrogen peroxide using INH-PC [Iso-Nicotinicacid Hydrazide- Pyrocatechol] system 10 . he using of H 2 O 2 , INH-PC reagent system produced a chromogenic complex with *Author for correspondence Indian Journal of Science and Technology, Vol 9(4), DOI: 10.17485/ijst/2016/v9i4/80499, January 2016 ISSN (Print) : 0974-6846 ISSN (Online) : 0974-5645