The　remediation　of　organic-contaminated　water　is　a　critical　environmental　challenge,　and　iron-based　persulfate　(PS)　activation　processes　have　emerged　as　a　promising　solution.　However,　the　introduction　of　reductive　sulfur　species,　while　accelerating　the　Fe(III)/Fe(II)　redox　cycle,　may　also　quench　reactive　species,　potentially　compromising　the　efficiency　of　Fenton-like　systems.　Here　we　systematically　investigate　the　trade-off　between　accelerated　Fe(III)/Fe(II)　cycling　and　quenching　effects　in　the　zerovalent　iron/PS　(ZVI/PS)　system　using　thiosulfate　(TSF)　as　an　activator.　Our　results　show　that　low-level　TSF　(0.03–1.00　mmol/L)　effectively　facilitated　the　removal　of　naphthalene　(Nap)　and　atrazine　(ATZ),　respectively.　This　enhancement　is　attributed　to　accelerated　ZVI　dissolution　and　FeSx　formation,　which　promote　the　Fe(III)/Fe(II)　cycle,　with　Fe(IV)　was　identified　as　the　primary　active　species.　However,　high-level　TSF　(＞1.0　mmol/L)　drastically　reduced　Nap　removal　due　to　PS　consumption　and　active　species　elimination.　The　optimal　TSF　dosage　of　0.20　mmol/L　(TSF/PS　molar　ratio　of　1:10)　demonstrated　robust　organic　pollutant　degradation,　achieving　a　22-fold　increase　in　the　rate　constant　(kobs)　for　Nap　removal　and　0.47–7.5-fold　increases　for　ATZ　removal.　These　findings　highlight　the　potential　of　the　TSF-ZVI/PS　system　as　a　versatile　and　efficient　solution　for　degrading　a　wide　range　of　organic　pollutants,　including　PAHs　and　herbicides,　in　water　treatment　applications.　©　2025　Elsevier　Ltd