Electron　beam　radiolysis　experiments　were　undertaken　to　gain　insights　into　the　kinetic　mechanisms　of　diethyl　phthalate　(DEP)　degradation　in　aqueous　solutions.　DEP　degradation　was　found　to　follow　pseudo-first-order　kinetics.　The　pseudo-first-order　rate　constant　decayed　exponentially　with　DEP　initial　concentrations　(C-0),　whereas　G　values　of　DEP　and　C-0　followed　linear　relationship.　Addition　of　sodium　carbonate　to　irradiated　DEP　solutions　reduced　DEP　decomposition.　H2O2　was　not　favorable　for　removal　of　DEP.　An　effective　degradation　was　achieved　in　both　N2O-saturated　and　t-BuOH-containing　N-2-saturated　DEP　solutions.　High　removals　(＞99%)　were　achieved　at　15　kGy　without　these　radical　scavengers.　Radical　scavenging　tests　indicated　that　both　(OH)-O-center　dot　and　e(aq)(-)　played　significant　roles　in　DEP　radiolysis.　Several　intermediates　such　as　monoethyl　phthalate,　phthalate　acid,　and　short-chain　aliphatic　carboxylic　acids　were　formed　from　DEP　radiolytic　degradation.　Finally,　DEP　was　completely　mineralized　when　the　absorbed　dose　was　high　enough.　Results　also　indicate　that　electron　beam　radiolysis　is　a　promising　process　for　an　efficient　removal　of　DEP　in　aqueous　solutions.