A procedure was developed for the determination of deuterium concentration in brines and in hypersaline aqueous solutions, without the removal of alkaline earth metal cations. Aqueous salt solutions of nine salts, LiCl, NaCl, Nal, Na2CO3, KCl, K2SO4, CsCl, CaCl2 and Mg(ClO4)2, with molalities ranging from 0.5 to 11.8 mol kg–1 were prepared by dissolving the dry anhydrous salts in de-ionized water of known isotopic composition. Only 8 µl of sample were required to be reduced with zinc metal at 460 °C in a special glass container equipped with a Teflon stopper, to prepare hydrogen for isotopic analysis. The salts NaCl, Nal, Na2CO3, KCl, K2SO4 and CsCl required 0.25 g, LiCl and CaCl2 0.75 g and Mg(ClO4)2 1.00 g of zinc for complete reduction. Deuterium concentrations in brines containing large amounts of Ca2+, Mg2+, Cl– and SO42– ions were measured with an accuracy of ±1‰(1σ). In addition, the deuterium content in Dead Sea water was determined with the same method and gave δD =+ 5.4 ± 0.3‰ using 1.50 g of zinc.