This paper proposes hafnium (IV) oxide (HfO2) as gate oxide material of the nanowire junctionless transistor (NJT) to replace the conventional silicon dioxide (SiO2). Leakage current usually increased due to an increase of tunneling of electronsin SiO2transistor when the thickness oxide (tox) of the gate material is below 2nm. The main advantages of HfO2is high dielectric constant k of 20 to 25 which is almost 6 times than that of SiO2. Similarly, HfO2has an energy band gap of 5.3 to 5.7eV. As a result, low leakage current and short channel effects (SCEs) was experienced. An increased in the gate capacitance of the device leads to improve the performance of the device without affecting the enhanced leakage current. All these was achieved by designing and simulating the device using the SDE tools of Sentaurus TCAD. Electrical characteristics was extracted using the Sdevice tools of the software. The performance was significantly increased to approximately 1010using HfO2material