H2O2 and O3 when used in water under UV light is particularly well suited for the breakdown of organic molecules as the cleavage of the O-O bond gives OH radicals or "O" atoms. The OH radical is known to be extremely reactive with most organic molecules with H-atom donor properties and promptly attacks such species to produce new types of radicals which may subsequently initiate several radical chain reactions. Also OH radicals are more effective than OR and OOR radicals (R = aryl group) in producing carbon radicals from organics and hence the use of H2O2 as the source of free radicals is very attractive. This photo-oxidation is also called advanced oxidation or enhanced oxidation. Inspite of an extensive research carried out in this area, no reliable kinetic model is available. The UV dose has been changed in a number of studies but very few studies have actually measure the intensity, which of vital importance. Studies on the oxidative degradation of phenol present in dilute aqueous solution in the concentration range between 100 ppm and 1000 ppm with and without hydrogen peroxide were conducted in a batch reactor. The temperature was maintained at about 333 K by circulating cooling water through reactor jacket. Initial conversion of phenolic compounds was extremely high compared with the latter part of the reaction. In presence of hydrogen peroxide, conversion of phenol was found to increase with an increase in hydrogen peroxide / substrate ratio and decrease with increase in initial substrate concentration.