Abstract: The relative partial molar enthalpies △H_Hα→β for absoption of H₂ By LaNi₅, LaNi₄Cu and LaNi₄Fe have been measured respectively, using a calorimeiric system[1] at 298.3K. The values obtained are -3.590± 0.036, -3.905±0.038 and -4.049 ±0.041 Kcal/molH. Their △G_Hα→β have been also measured and their △S_Hα→β have been calculated. △H_Hα→β of LaNi₅ is in agreement with that cited in the literature[2] while those of LaNi₄Cu and LaNi₄Fe measured by calorimetry have not been reported as yet in literature. The lattice parameters of LaNi₅, LaNi₄Cu and LaNi₄Fe have been determined by X-ray diffraction analysis. The relations between △H_Hα→βHα→β, △G_Hα→βHα→β and unit cell volume Vare:△H_Hα→β= -0.2509V +18.25△GHα→β= -0.2258V + 20.02.