In this work, the influence of substituents in the structure of the diimine bridge of nickel polymer complexes with salen-type ligands on the rate of loss of their electroactivity in dried and water-containing electrolyte solutions was studied. It is shown that the presence of the four methyl groups, which leaves the complex plane, can significantly reduce the rate of electroactivity loss during cycling in a water-containing electrolyte (residual capacity of 37% relative to the initial one after 50 cycles) compared to unsubstituted poly[Ni(salen)] (residual capacity of 15%), and complexes containing only one methyl group and methyl groups in alpha positions of the diimine bridge (retaining of 5% and 0% of residual capacity by after 50 cycles, respectively). It was shown that in all cases, when cycling in a water-containing electrolyte, in parallel with the loss of capacity of the polymer films, their mass increases.