Thin tris(acetylacetonate)manganese(III) films of amorphous structure were prepared by vacuum deposition on glass and Si (10 0) substrates. The as-deposited and annealed-in-vacuum films were characterised by X-ray fluorescence, X-ray diffraction and optical absorption spectroscopy. The prepared title-complex amorphous films were investigated as insulators for Al/insulator/Si(P) metal-insulator-semiconductor (MIS) structures, which were characterised by the measurement of their capacitance and AC-conductance as a function of gate voltage. From those measurements, the state density D-it at insulator/semiconductor interface and the density of the fixed charges in the complex insulator were determined. It was found that D-it was in order of 10(11) eV(-1) cm(-2) and the surface charge density in the insulator film was in order of 10(11)-10(12) cm(-2). The frequency dependence of the electrical conductivity and dielectric properties of MIS structures were studied at room temperature. The results follow the correlated barrier-hopping (CBH) model, from which the fundamental absorption bandgap, the minimum hopping distance and other parameters of the model were determined. This study shows that the tris(acetylacetonate)manganese(III) films grown on Si(100) is a promising candidate for high-epsilon dielectric applications. It displays sufficiently high-8 value in the range 30-40. (c) 2005 Elsevier B.V. All fights reserved.