Ryan Andrew King was sought out by the men after advertising castration services although his only medical qualification was an advanced first aid certificate, a Brisbane court heard on Friday.

The 28-year-old offered the services through a eunuch website for people interested in the modification of male genitalia.

Both men wanted the surgery, but it was not available to them in any lawful way, the Brisbane District Court was told.

One of the men said the procedure benefited his health and well-being as he had suffered from genitalia dysphoria.

"I am eternally grateful to Ryan for enabling me to enjoy life," the 65-year-old said in a statement handed to the court.

King wasn't paid, but filmed one procedure - with the man's consent - on the basis he could publish the video on the same site.

One amateur surgery took place in a motel in Loganholme south of Brisbane in February 2019 when King removed the 65-year-old man's testicle.

The pair had met the previous year when King removed his penis and other testicle, but that procedure was performed in Victoria so it is not the subject of charges in Queensland.

King performed the second procedure on a 26-year-old Chinese national, who wanted to be gender neutral, in a Brisbane backpackers hostel in July last year.

The man flushed the testicle down a toilet - so it could not be retrieved and re-attached - after the one-and-a-half hour surgery.

Both men were treated for bleeding in hospital afterwards, but that was part of the plan, the court was told.

"The desire was ... that they be taken by the defendant beyond the point of no return ... so they could not be repaired," defence barrister Christopher Wilson said.

The older man told health authorities at that time he had performed the surgery himself.

But the foreign man contacted King to help stem the bleeding after discovering he wasn't eligible for Medicare.

King called paramedics and then admitted to police he had performed the surgery.

Officers searched King's house finding medical equipment and the older man's genitalia in a freezer.

Mr Wilson said at the time of his arrest King was unaware consent did not exonerate him, although that was no defence.

"He has not acted in deliberate defiance of the law," he added.

Judge Richard Jones said a psychiatric report handed to the court described King's history and conditions from which he suffers.

"There was little doubt you had an extremely troubled childhood," he said.

King who had no previous criminal history pleaded guilty to both charges of committing malicious acts with intent.

The plea was "reflective of remorse and no doubt the level of shame" King feels about what he has done, Judge Jones said.

But King must have known his actions were against the law.

"You were clearly not authorised or even qualified to perform what you did," he told King in handing down his sentence.

General deterrence was important in sentencing King.

"The message must be sent to people in the community that you cannot do things like this," Judge Jones added.

He sentenced King to three-and-a-half years behind bars, but ordered he be released immediately on probation.

King has been in custody since his arrest in July last year.

Australian Associated Press