The antioxidant capacity of foods, medicines and their supplements can be estimated by following procedures of certain methods involving spectrophotometer which is discussed here. The methods followed have been slightly modified sometimes, to suit the needs of botanicals. All the procedures, given here require spectrophotometer to asess the ability of absorbance. The significance of antioxidants in diets, medicines and nutraceuticals is enumerated. Each method has its own ability of reacting with either reductants or enzymes, or free radicals.Thus antioxidant capacity requires two or three methods to assess the capacity of antioxidants present in foods and medicines.