Detectives have charged a 32-year-old woman with grievous bodily harm following investigations into the alleged assault.

The Larapinta (Northern Territory) woman was due to appear before the Mount Isa Magistrates Court today, but instead the court was told she was in the mental health ward at Mount Isa Hospital.

Police allege that at 8.15pm on Tuesday, a 51-year-old man was at his residence in Railway Street when an argument broke out with the woman, who is known to him.

A physical altercation then ensued and the woman allegedly punched the man in the head, causing him to fall and hit his head on the cement driveway.

The man was transported to the Mount Isa Hospital where he remains in a critical condition with serious head injuries.

Mount Isa District Criminal Investigation Unit is still preparing paperwork, including an objection to bail.

Police prosecutor Sergeant Karen Hall told the court that prosecution and investigators can travel to the mental health ward to see the defendant if necessary.

The Magistrate said he would await paperwork from police before proceeding.