The pH-dependent H-1 NMR characteristics of a series of Co-III-(polyamin)-aqua and Co-III-(polyamin)-(polyalcohol) complexes, [Co(tach)(ino-kappa(3)-O-1,O-3,O-5)](3+) (1(3+)), [Co(tach)(ino-K-3-O-1,O-2,O-6)](3+) (2(3+)), [Co(tach)(taci-kappa-N-1-kappa(2)-O-2,O-6)](3+) (3(3+)), [Co(ditame)(H2O)](3+) (4(3+)), and [Co(tren)(H2O)(2)](3+) (5(3+)), were studied in D2O by means of titration experiments (tach = all-cis-cyclohexane-1,3,5-triamine, ino = cis-inositol, taci = 1,3,5-triamino-1,3,5-trideoxy-cis-inositol, tren = tris(2-aminoethyl)amine, ditame = 2,2,6,6-tetrakis(aminomethyl)-4-aza-heptane). A characteristic shift was observed for H(-C) hydrogen atoms in the a-position of a coordinated amino group upon deprotonation of a coordinated oxygen donor. For a cis-H-C-N-Co-O-H arrangement, deprotonation of the oxygen donor resulted in an additional shielding (shift to lower frequency) of the H(-C) proton, whereas for a trans-H-C-N-Co-O-H arrangement, deprotonation resulted in a deshielding (shift to higher frequency). The effect appears to be of rather general nature: it is observed for primary (1(3+) -5(3+)), Secondary (4(3+)), and tertiary (5(3+)) amino groups, and for the deprotonation of an alcohol (1(3+)-3(3+)) or a water (4(3+), 5(3+)) ligand. Spin-orbit-corrected density functional calculations show that the high-frequency deprotonation shift for the trans-position is largely caused by a differential cobalt-centered spin-orbit effect on the hydrogen nuclear shielding. This effect is conformation dependent due to a Karplus-type behavior of the spin-orbit-induced Fermi-contact shift and thus only significant for an approximately antiperiplanar H-C-N-Co arrangement. The differential spin-orbit contribution to the deprotonation shift in the trans-position arises from the much larger spin-orbit shift for the protonated than for the deprotonated state. This is in turn due to a trans-effect of the deprotonated (hydroxo or alkoxo) ligand, which weakens the trans Co-N bond and thereby interrupts the Fermi-contact mechanism for transfer of the spin-orbit-induced spin polarization to the hydrogen nucleus in question. The unexpectedly large long-range spin-orbit effects found here for 3d metal complexes are traced back to small energy denominators in the perturbation theoretical expressions of the spin-orbit shifts.