The cloud point extraction (CPE) method has been applied to the extraction and pre-concentration of Mg2+ ions. The extracted solvated species showed a maximum absorbance at λmax = 249 nm. The optimum conditions for extraction of solvated species to CPL are the presence of 0.5 M KNO3 for 50 μg Mg2+ ion in 10 ml aqueous solution with 1×10-4 M of extractant, 2,4-dimethyl-pentan-3-one (2,4-DMP) and heating up to 90 °C for 15 minutes and addition of 0.5 mL of 1 % Triton X–100 as surfactant. The study showed that different extractant have different extraction efficiency, acetophenone showing higher extraction efficiency but ethyl methyl ketone has a lower efficiency. The effect of different salts and variable concentration of nitrate salts on the extraction efficienct has been studied. Determination of Mg2+ in different samples has been studied with a RSD = 0.0074, DL = 1.84×10-5 and Sandel’s sensitivity = 3.58 ×10-9 μg cm-2.