The Ni/Al2O3/InAlN/AlN/GaN metal-oxide-semiconductor heterostructure (MOS-H) is investigated using capacitance-voltage and capacitance-time characteristics in the temperature range of 25-300 degrees C. An anomalous positive voltage shift of the capacitance-voltage curve with increasing temperature was observed and attributed to the hole emission from the oxide/semiconductor interface states. Distribution of the interface states density, Dit(E), at the Al2O3/InAlN interface was evaluated using a modification of the constant-capacitance deep-level transient spectroscopy. The MOS-H capacitor threshold voltage shift under negative bias was repetitively recorded as a function of time at elevated temperatures. Dit in the range of 0.1-3 x 10(13) eV(-1) cm(-2) was determined.