Thermodynamic quantities were determined for the absorption of hydrogen in Pd-5.5at.%Li and Pd-7.2at.%Li alloys, the latter alloy being in the two-phase field of saturated α-Pd(Li,s) solid solution and the ordered Pd 7Li phase. Data were also determined for the Pd-10.6at.%Li alloy which consists only of the ordered Pd 7Li phase. The data were determined from measurements of pressure-composition isotherms at temperatures between 273 K and 463 K and hydrogen pressures up to 1000 Torr. The PdLi alloys dissolve considerable amounts of hydrogen and form a more stable hydride phase than Pd despite the lattice contraction which occurs on alloying Pd with Li. The hydrogen solubility in the ordered Pd 7Li phase alone is a little smaller than that in the two-phase mixture. The large hydrogen absorption of PdLi alloys, which does not depend on the presence of ordered Pd 7Li, may be attributed to (i) an attractive HLi pair interaction, (ii) a decrease in the strain energies necessary for hydrogen occupation of the interstices, because of the similar lattice parameters of the α-Pd(Li,s) and ordered Pd 7Li phases, and the large compressibility of PdLi alloys, and (iii) the valence of 1 of Li in Pd compared with 3 for, for example, Y in Pd.