The properties of carbon paste electrodes (CPEs) modified chemically with selected Ni-azamacrocyclic complexes, both soluble and insoluble in water, have been studied by cyclic voltammetry in solutions of various supporting electrolytes. In the case of CPEs modified with Ni-cyclam and with an Ni-tetraaza-macrocyclic complex containing a pendant amino group the effect of the coordination of the inorganic anions has been studied and discussed. It has been found that Ni-cyclam-modified CPEs act as an effective catalyst for the oxidation of H2O2 in neutral solutions.