The review describes the state of the art in the field of stability constant determination for Cu(II), Cu(I) and Zn(II) complexes of proteins and peptides involved in neurodegenerative diseases, α-synuclein (aS), prion protein (PrP), amyloid precursor protein (APP) and amyloid β peptides (Aβ). The methodologies and results are critically analyzed and recommendations are formulated about possible systematic errors in these studies. The possibility of formation of ternary complexes with titration competitors is discussed.