A man has been charged with grievous bodily harm over a one-punch attack on a woman in Mount Isa which left her with critical head injuries.

Police alleged the attack happened at the main entrance of The Buffs at midnight. ( ABC News: Zara Margolis )

Queensland Police said at 12:00am, a 36-year-old Happy Valley employee of The Buffs Club on Grace Street was at the main entrance when she was approached by a man who had been refused entry.

The employee was speaking with another woman when she was allegedly assaulted by the man, who was allegedly intoxicated, causing her to fall the ground, hitting her head.

Detective Senior Sergeant Alex McBroom said the man then fled the scene but he was apprehended about an hour later.

The woman was taken to Mount Isa Hospital with critical head injuries and was flown to Townsville Base Hospital later in the day by the Royal Flying Doctor Service.

"We are very hopeful she is going to make a good recovery however her injuries are considered very serious, they're potentially life threatening but her condition at this time is stable," Snr Sgt McBroom said.

"[She is] a family person who is going to work and going about her duties as any other person in the community. She deserves the right of safety."

A 28-year-old Parkside man is scheduled to appear at Mount Isa Magistrates Court on January 11.