In this work, the authors developed the complex impedance spectroscopy (CIS) technique to study ac electronic properties and nanostructure characteristics of magnetic tunnel junctions (MTJ) based on trilayer thin films Co/Co-Al2O3/Co - a hybrid type between a single MTJ, such as Co/Al2O3/Co, and a nanogranular thin film Co-Al2O3 played the role of an inserted barrier layer - the so called hybrid-type MTJ, or HMTJ. The HMTJs prepared by sputtering technique with various thicknesses, from 20 to 130 nm, and various component of atom Co of the Co-Al2O3 inter/ayers, from 8 percent to 35 percent. The CIS characteristics ar,e investigated in various intensities of external magnetic field applied on these HMTJs.