It's understood the man – who was from Dublin and had been living and working in Australia for a number of years – was attacked by another man at a restaurant in Sydney last night.
A woman who was with him was also injured in the incident.
A man – in his forties – has been arrested and was taken to Hornsby Police Station.
It's reported he's been charged with murder and attempted murder and will appear in court later.
The Department of Foreign Affairs says it has received NO request for consular assistance in the case.
