A Queensland prisoner who scalded schoolboy Daniel Morcombe's killer with a bucket of boiling water has been sentenced to three years' jail.

Adam Paul Davidson, 31, pleaded guilty in the Brisbane District Court on Monday to torturing Brett Peter Cowan at the Wolston Correctional Centre on August 5, 2016.

Daniel Morcombe's killer Brett Peter Cowan was scalded with hot water in an act of prison retribution, a court has heard.

Judge Ian Dearden sentenced Davidson to three years' jail but with time already served he will be released on parole in late November.

The court heard Davidson plotted and watched Cowan's movements for a month to find the best way to harm the high-profile sex offender.