Thin filmsofZn40Se60 were preparedbythevacuumthermalevaporationtechnique.Theinfluenceof annealedtemperatureonthestructuralandopticalpropertieswasinvestigatedusingtheX-ray diffraction(XRD),scanningelectronmicroscopy(SEM)andopticaltransmission.TheXRDstudiesshow that theas-depositedfilmisamorphousinnature,butthecrystallinityimprovedwithincreasingthe annealingtemperature.Furthermoretheparticlesizeandcrystallinityincreasedwhereasthedisloca- tion andstrainsdecreasedwithincreasingtheannealingtemperature.SEMstudiesshowedthatthe annealingtemperatureinducedchangesinthemorphologyoftheas-depositedsample.Variousoptical constanthavebeencalculatedforas-depositedandannealedfilms.Themechanismoftheoptical absorptionfollowstheruleofdirecttransition.Itwasfoundthat,theopticalenergygap(Eg) decreased with increasingtheannealingtemperature.TheseresultscanbeinterpretedbytheDavisandMotte model. Ontheotherhandthemaximumvalueoftherefractiveindex(n) isshiftedtowardthelong wavelengthbyincreasingtheannealingtemperature.