The stable isotopes of oxygen (δ¹⁸O) and hydrogen (δD) of calcium sulfate hydration water (e.g., gypsum - CaSO₄·2H₂O; bassanite - CaSO₄·0.5H₂O), can be used to reconstruct evaporative conditions as well as estimate moisture sources. We developed a novel method for the δ¹⁸O and δD analysis of calcium sulfate hydration water which requires significantly lower amounts for analysis (~1 to 2 mg) compared to previous methods. These lower sample weight requirements prove valuable for gypsic-saline soil studies, as they both remove previous limitations of bulk measurement and improve spatial resolution. Reg soils, which are common in the hyper-arid southern Negev Desert, are abundant in evaporates, namely halite and calcium sulfates (gypsum, bassanite, anhydrite). Pedogenic gypsum and halite precipitated following the evaporation of meteoric-derived waters and accumulated in the subsurface due to minimal leaching. We measured calcium sulfate hydration water stable isotopes found 0 - 150 cm below the surface in a Reg soil section from Shehoret (Eilat). Preliminary results indicate substantial very high and variable δ¹⁸O values along the profile (+9.7‰ to +12.0‰) with ΔδD/Δδ¹⁸O slopes that reflect both the isotopic composition of meteoric water source and evaporation, consistent with the expected trends in hyper-arid soil environments (slope ~ 2 to 5). These novel pedogenic calcium sulfate isotope results prove promising for the reconstruction of local paleo-climate conditions and better understanding the formation and accumulation of soluble salts in general and calcium sulfates in particular in arid soils.