The current study describes a simple, precise, and accurate protocol for measuring the activity of catalase, which controls the rate-limiting step of the dissociation of hydrogen peroxide reactions. The current protocol assesses catalase activity by incubating catalase samples with suitable concentrations of hydrogen peroxide dissolved in a phosphate buffer (pH 7.4). After the incubation period, a working solution that contained vanadate (V) and pyridine-2,6-dicarboxylic acid was added to stop the enzymatic reaction. The reaction between undissociated hydrogen peroxide and the added reagent forms a stable orange-colored chelate complex known as oxo-peroxo-pyridine-2,6-dicarboxylato-vanadate (OPDV) that demonstrates maximum absorbance at 435 nm. To optimize the formation of the method (the OPDV-CAT assay), we applied the Box–Behnken design (BBD) by utilizing the response surface methodology (RSM) as an index of precision of the assay. This novel method was validated against a Bland–Altman plot analysis of catalase activity using the carbonato-cobaltate method in matched samples. The comparison between the two methods resulted in a correlation coefficient equal to 0.9968, demonstrating that the new method is just as effective as the reference method.