Hydroxy davyne is a hydrated aluminosilicates with the same structure as cancrinite mineral group. Scientist categorized hydroxy davyne as zeolite because of its low temperature formation conditions and hydrated structure. Existence of [Ca.Cl] ⁺ group instead of [Na.H₂O] ⁺ group is the significant property of this mineral. Alteration of volcanic ash in presence of alkaline hydrothermal solutions is a common procedure to originate zeolite minerals. Therefore the aim of this research is to estimate of hydroxy davyne formation through phase transition of volcanic ash in the presence of alkaline solutions at hydrothermal conditions. The results of this research show that hydroxy davyne originate at 150 °C in the presence of alkaline hydrothermal solutions with high concentration of Na⁺, K⁺ and Cl^-.