The present work aimed to evaluate some eco-physiological responses of Alhagi graecorum to elucidate its osmotic adjustment and physiological adaptation mechanisms to withstand hyper-aridity. The plant samples were collected from eight locations in the Dakhla Oasis during the winter and summer of 2017. The chlorophyll (Chl a & b) contents and their ratio increased significantly during summer enabling the plants to adapt to light condition changes. There was a greater accumulation of anions and cations in plant tissues during winter more than in summer except, for K ⁺that exhibited the opposite trend during summer. Soluble sugars (SS) and soluble proteins (SP) were higher than total free amino acids (TAA) during summer. The total phenolics (Ph) and total antioxidants (Anti. Ox.) in this plant were higher during winter than in summer; whereas total flavonoids (Flav) displayed the opposite response.