Abstract The transition between the spherical and deformed shapes of the nuclei (shape phase transition) is an interesting property of nuclei that enriches our understanding of the nuclear structure. One method for studying it is through measurement of a wide range of atomic masses and derivation of the two-neutron separation energies (S2n). Using a multiple-reflection time-of-flight mass spectrometer at the FRS Ion Catcher, GSI, atomic masses in the region of A~150 were measured. This allowed an wide study of phase shape transitions in this region of the nuclear chart. In addition, comparison with the Skyrme Hartree-Fock plus BCS approach are done; showing a remarkable good agreement between theory and experiment.