A new series of hexadentate thioether-containing ligands was designed. Five nickel(II) dicationic pseudo-octahedral complexes synthesised with them revealed different degrees of deviation from ideal geometry. The electronic absorption spectra confirm the formation of high-spin octahedral [NiN4S2]2+chromophores with a large covalency typical for Ni(II) thioether complexes. DFT calculations help assign the chelating agent transitions, and support the Ni(II) high-spin ground state assignments, while suggesting that the SOMOs have mainly ligand character. The electrochemical behaviour of the complexes is consistent with irreversible n = 1 redox processes around −1.0 V, formally assignable to the Ni(II)/Ni(I) couple. Ligand reduction and large current augmentation due to catalytic H2production are also observed in this region.