In this work, a cutting tool with premature wear was characterized by Rockwell hardness test, scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). In addition, electrochemical impedance spectroscopy (EIS) measurements were carried out in order to investigate the characteristic properties of the wear coating (TiAlN) of tool (WC–Co substrate). The substrate hardness was 90 HRA, which is in accordance with the observed microstructure of a cobalt matrix with tungsten carbides. SEM-EDS analysis confirmed the presence of a TiAlN coating and of typical features of an adhesive wear mechanism. EIS results revealed typical behavior of a porous WC–C substrate. Hence, premature wear of cutting tool could be explained in terms of an inadequate performance of the defects of coating deposited on the WC-Co substrate, as suggested by porosity revealed in the SEM images and the EIS measurements.