In this study, in-situ high-temperature loading investigations will be performed to characterise the micromechanics of a high strength alloy 720Li, during stress relaxation in the vicinity of 750C under uniaxial stresses of a few hundred MPa, in addition to the internal stress development, which provides an alternative time-efficient approach to assess the creep properties of the material. Additional studies will assess the stress development during post solution treatment aging, which is believed to shed some light on the mechanism for strain age cracking. The main objective is to examine the influence of the gamma/gamma' interactions on the high temperature micromechanics and their impact on the structural integrity of Ni-based superalloys. The proposed investigations are expected to provide the data needed for testing and validation of creep deformation and cracking models.