The secondary nitrogen donors of the Ni(II) complexes of macrotricyclic ligands 8-methyl-1,3,6,8,10,13,15-heptaazatricyclo $[13.1.1.1^{13,15}]$octadecane (A) and 1,3,6,9,11,14-hexaazatricyclo $[12.2.1.1^{6,9}]$octadecane (B) are N-alkylated and the Ni(II) complexes of $N-Me_2A,;N-Et_2A,;and;N-Me_2B$ are obtained. The Ni(II) complexes of $N-Me_2A;and;N-Et_2A$ are stable in acidic aqueous solutions while that of $N-Me_2B$ decomposes relatively rapidly. The N-alkylation leads to the decrease in the ligand field strength as well as an anodic shift in both of the oxidation and the reduction potentials of the Ni(II) complexes.