They allege the surgery took place after a 52-year-old man placed an advertisement online seeking help with a medical issue.
The accused responded to the advertisement and the pair met in May at a Port Macquarie motel, where the 56-year-old man allegedly performed a surgical procedure to remove the 52-year-old’s left testicle.
Authorities were alerted one week later, when the patient visited a hospital to repair a wound he sustained during the procedure.
Police said the accused was not a qualified or registered doctor.
He has been charged with assault occasioning grievous bodily harm, possessing a restricted substance and unsafely storing a firearm.
He will appear in court on 13 July.