Gold nanoclusters protected by ligands present well-defined compositions and tunable structures, which builds a solid basis for correlation between structures and properties. We report a combined ion mobility-mass spectrometry approach for the analysis of ultra-small gold nanoclusters protected by glutathione (SG) as ligand molecules, Au10-12(SG)10-12. Collision cross section (CCS) measurements are reported for different charge states for Au10(SG)10, Au11(SG)11 and Au12(SG)12 nanoclusters. Computational calculations, at the PM7 semi-empirical level of theory, are performed to optimize geometrical structures and use them to compute CCS. The comparison of the experimentally and theoretically determined CCS allows drawing conclusions on the structural changes, in particular partial unfolding of SG ligands, upon charging. Introduction: