Abstract: The p-c-T curves of titanium absorbing hydrogen,deuterium and tritium are measured on thermodynamics and kinetics measuring system of metal hydride. According to the Van't Hoff E-quation the thermodynamics parameters of the different phases are determined. The experiments indicate that there are obvious thermodynamics isotope effects when titanium absorbing hydrogen, " deuterium and tritium. The order of equilibrium pressure absorbing gases is 3H>2H>1H. However, the enthalpy and entropy appears to be in verse order, 3H<2H<1H.