Spectrophotometric　method　is　a　simple　and　effective　in　situ　analytical　method　for　contaminants　monitoring,　but　further　improvement　of　its　sensitivity　and　detection　limit　for　radionuclides　determination　remains　highly　desirable.　Herein,　we　report　a　simple　and　highly　sensitive　thiocyanate　spectrophotometric　method　for　the　determination　of　radioactive　Tc(VII)　by　studying　its　chemical　analogue　Re(VII)　in　different　aqueous　media.　The　colorless　thiocyanate　reacted　with　Re(VII)　in　hydrochloric　acid　solution　in　the　presence　of　SnCl　2　producing　a　stable　colored　Re(IV)-SCN　complex,　which　was　extracted　into　ethyl　acetate　and　then　measured　at　427 nm.　Under　optimized　conditions,　a　strong　linear　relationship　can　be　obtained　in　the　range　of　0.25–10 mg L　−1　for　Re(VII)　with　R　2　value　>　0.9942,　and　the　sensitivity　of　the　method　was　found　to　be　0.004 μg cm　−2　with　detection　limit　of　0.027 mg L　−1　.　This　assay　provides　highly　sensitive　detection　of　Re(VII)　in　environmental　media　that　is　high　in　NO　3　−　,　Cu　2+　,　and　Fe　3+　.　We　applied　it　to　the　determination　of　Re(VII)　in　the　wide　range　of　background　solutions,　including　deionized　water,　groundwater,　and　seawater,　and　analysis　results　showed　that　none　of　the　molar　absorptivities　for　both　groundwater　and　seawater　backgrounds　was　statistically　different　from　the　deionized　water　background　when　the　paired　Student’s　t　test,　at　95%　confidence　level,　was　applied.　The　operational　simplicity,　accuracy,　and　precision　of　the　proposed　method　suggest　that　it　can　be　a　good　alternative　for　the　in　situ　analysis　of　pertechnetate　in　environmental　media.　©　2018,　Institute　of　Chemistry,　Slovak　Academy　of　Sciences.