Sheffield Crown Court heard how in the moments before Clive Martindale carried out the shocking attack at HMP Lindholme on June 26 last year, his victim had locked himself in his cell.
He subsequently went up to his cell door after some fellow inmates initiated a conversation with him there, and began speaking with them through the door's broken access window.
"This defendant went up to the cell door with a cup of boiling water, which must have been brought from a nearby cell with a kettle, and threw it through the hatch, and on to the complainant's face," said Gordon Stables, prosecuting.
He added: "He was caused immediate pain, and sustained blistering burns to his face."
Martindale's victim suffered 'superficial burns to his forehead, nose and cheeks', and still had visible scars from them some six months on, added Mr Stables.
In a victim impact statement read out in court, the man said he had only been on the wing for three days, and only knew one person at the prison when the attack occurred.
"Whilst I am a serving prisoner, and expect a certain level of animosity, this level of violence is way beyond what can be deemed as reasonable. This was completely unprovoked," said the man, adding: "I still have pain in my face."
Martindale, who was serving a five-and-a-half-year sentence for robbery and criminal damage when he carried out the scalding, pleaded guilty to a charge of assault occasioning actual bodily harm at an earlier hearing.
In mitigation, Martindale's barrister, Glenn Parsons told the court that Martindale's victim was 'not without blemishes' and had been 'throwing his weight around on the wing' since arriving there.
"Your Honour can take into account there was some degree of provocation," said Mr Parsons, adding that while Martindale, 26, has a history of violent offences this was the first time he had committed such a crime in a prison environment.
Recorder James Baird sentenced Martindale, of HMP Lindholme, to another 12-months in prison.
He said: "I don't know what was behind it, but what I do know is there is no justification for such a nasty attack."