Selective and efficient separation of 90^Sr from high level waste solution of high salt content will pave the way to Manage a problematic waste and also for utilization of recovered ⁹⁰Sr for societal purpose. In the present work, a process for selective separation of 90Sr is described using 4,4′(5′) - [di-tert-butyldicyclohexano]-18-crown-6 (DtBuCH18C6) dissolved in an industrial diluents system: isodecyl alcohol + n-dodecane. The process ssolvent is optimized as 0.1 M DtBuCH18C6 + 50% isodecy lalcohol/n-dodecane for satisfactory extraction of strontium at higher nitric acid concentrations (D_{4-8 M HNO3} =5–4). Stoichiometry determination by slope analysis method showed 1:1:1M ratio for Sr²⁺, DtBuCH18C6 and HNO₃ in the extracted complex. Among the inert and active constituents of the waste, extraction of plutonium (IV) (D_Pu = 0.3) and barium (D_Ba = 0.7) was observed to some extent, extraction of calcium was almost negligible (D_Ca = 0.01) while no extraction of americium, cesium, ruthenium, niobium, zirconium and lanthanides was observed. Stripping of the loaded organic was achieved by deionized water, three consecutive contacts each with fresh deionized water results in complete stripping of strontium.