Seven more prisoners have been charged over last month's riot at Goulburn Jail.

Thirty prisoners attacked guards with broken table legs, didgeridoos and other items of furniture from their cells, injuring seven officers, one seriously.

Seven men have appeared in Goulburn Court charged with rioting and several counts of assaulting an officer.

Their cases have been adjourned until June 19.

Four other prisoners appeared in court last month, three charged with attempted murder.

Meanwhile, the condition of a prison guard injured in the incident appears to have improved.

Tim Swain sustained head injuries and had been in a critical condition in the Canberra Hospital but that has now been downgraded to serious.