The　reactions　of　the　pharmaceutical　fluoxetine　(FLX)　with　different　radicals　were　investigated　by　pulse　radiolysis.　The　reaction　of　hydroxyl　radical　(center　dot　OH)　with　FLX　formed　hydroxylated　adduct　of　the　aromatic　ring,　while　oxidation　of　FLX　by　sulfate　radical　anion　(SO4　center　dot-)　formed　benzene　radical　cation　that　further　reacted　with　H2O　to　yield　the　center　dot　OH　adduct.　The　determined　rate　constants　of　center　dot　OH,　hydrated　electrons　(e(aq)(-)),　and　SO4　center　dot-　with　FLX　were　7.8　x　10(9),　2.3　x　10(9),　and　1.1　x　10(9)　mol.L-1.s(-1),　respectively.　In　the　steady-state　radiolysis　study,　the　degradation　of　FLX　in　different　radiolytic　conditions　by　electron　beam　irradiation　was　detected　by　HPLC　and　UV-Vis　spectra　techniques.　It　was　found　that　FLX　concentration　decreased　by　more　than　90%　in　both　N2O　and　air-saturated　solutions　after　1.5　kGy　irradiation.　In　contrast,　only　43%　of　FLX　was　decomposed　in　N-2-saturated　solution　containing　0.1　mol.L-1　tert-butanol.　The　degradation　rates　of　FLX　in　acidic　and　neutral　solutions　were　higher　than　those　in　alkaline　solutions.　Our　results　showed　that　the　degradation　of　FLX　is　optimal　in　air-saturated　neutral　solution,　and　center　dot　OH-induced　degradation　is　more　efficient　than　SO4　center　dot-　oxidation　of　FLX.　The　obtained　kinetic　data　and　optimal　conditions　give　some　hints　to　understand　the　degradation　of　FLX.