Objectives: In this study, a unipolar corona discharger was developed and experimentally evaluated for its intrinsic and extrinsic charging efficiencies, and electrostatic and diffusion losses of submicron aerosol particles in the size range of 20–300 nm at different corona and ion trap voltages. Method: The applied voltage of the discharger ranged between 2.4 and 3.2 kV, corresponding to a discharge current of 0.19 nA–2.0 mA, and an ion number concentration of 1.88X1011–1.97X1015 ions/m3. Findings: Increasing the corona voltage could lead to a higher discharge current and ion concentration inside the discharger. In the proposed discharger, intrinsic charging efficiencies of aerosol particles between 76.9% and 93.0% were obtained for particle sizes ranging between 20 and 100 nm for the given corona and ion trap voltages. The extrinsic charging efficiency decreased as the ion trap voltage increased at a given corona voltage. Novelty: The optimal extrinsic charging efficiency of the discharger was observed to be approximately 20.8–58.6% for particle sizes ranging from 20 to 300 nm at a corona voltage and ion trap voltage of approximately 2.8 kV and 200 V, respectively. In this discharger, the highest electrostatic losses (approximately 73.5%, 83.7%, and 54.0%) were observed corresponding to corona voltages of 2.8, 3.0, and 3.2 kV, respectively at a particle diameter of 20 nm and an ion trap voltage of 300 V. Finally, the highest diffusion loss (approximately 18.9%) was observed at a particle diameter of 20 nm. Keywords: Corona discharge; particle charging; aerosol discharger; particle loss