A 53-year-old Gold Coast man allegedly assaulted by his son in a one-punch attack has died in hospital.

Mark Bradley McGrice was allegedly punched in the face by his 25-year-old son Morgan Isles-English in Brisbane's CBD on Monday afternoon.

The alleged blow caused him to fall back, hitting his head on the footpath.

He was taken unconscious to the Royal Brisbane and Women's Hospital with life-threatening injuries but died this afternoon.

Isles-English faced the Brisbane Magistrates Court on Tuesday morning charged with grievous bodily harm.

He did not apply for bail and was remanded in custody to appear in court again on August 15.

Police are considering upgrading the charge.