Dependence of the magneto-optical properties on the size and on the dielectric environment of a system consisting Ni nanowires embedded in an alumina matrix was analyzed. The system underwent some enhancement due to a surface plasmon resonance of the Ni nanowires, where as its spectral position depended on the wire diameter. The samples that are used were hexagonal arrays of nickel embedded in alimina membranes obtained by anodization of aluminum foils. The presence of the non-zero off-diagonal element makes the polarization plane of both the reflected and the transmitted light to be rotated with respect to that of the incident one. The origin of the enhancement and the structure of Kerr rotation was observed. Results showed that the origin is fully compatible with a plasmon-like structure that propagates along the ferromagnetic wire.