The Folin-Ciocalteu’s phenol reagent is widely used in biochemical and analytical chemistry for the quantification of phenolic compounds. It is a key component in the Folin-Ciocalteu assay, which is employed to measure total phenolic content in various samples, including plant extracts, food products, and beverages. This reagent reacts with phenols to produce a blue-colored complex, the intensity of which can be measured spectrophotometrically to determine phenol concentration. Its application is particularly significant in the food and beverage industry for assessing antioxidant capacity, as phenols are often associated with health benefits. Additionally, it is used in research to study the phenolic composition of natural products and to evaluate the efficacy of antioxidants in pharmaceuticals and cosmetics. The reagent’s versatility and reliability make it a standard tool in phenolic analysis.