Prison staff found the man, who is on remand for rape, dead in his cell at the Arthur Gorrie Correctional Centre just before 11am (AEST) on Thursday.
Medical staff attended but he was declared dead at 11.20am.
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It is the second prison death in Queensland this week and the third death in custody in the past six weeks.
On Tuesday, a 42-year-old child sex offender was found dead in his cell at Wolston Correctional Centre in Brisbane's west.
An 18-year-old Aboriginal man on remand at the Arthur Gorrie Correctional Centre died at a Brisbane hospital on February 20.
His family claims he died after being denied requests for medical help while in jail.
All three deaths are being investigated by the coroner and chief inspector of prisons.
