Abstract Many-body perturbation theory has been applied to investigate the properties of lithium clusters which model the (111) surface of the crystal lattice. Hydrogen interaction with the clusters has been investigated in detail by considering different approach positions of the hydrogen atom. Important differences as well as some points of agreement have been found with previous results for similar work on Li n clusters in bcc(100) and (110) symmetries. Relative stabilities from the points of view of cohesive energy for bare clusters and chemisorption energy for hydrogen-lithium systems have been discussed. Charge transfer and p-occupancy effects for the various HLi n systems are presented in detail.