Patrick Farrell, aged 57 and originally from Derry, is accused of killing bar and budget hotel owner Ernest Brennan from Dublin.
Mr Brennan, from Howth in north Dublin, died after being stabbed in the Pattaya beach resort bar, Jimmy’s Place, which the 45-year-old ran with his Thai wife.
It has been reported that the pair were involved in an argument over the price of a taxi fare and hotel room shortly before the fatal stabbing. Farrell remained at the scene to wait for police to arrive. He was arrested at the scene and taken to Pattaya Police Station.
Thai police said the Derryman has been charged with murder and investigations are continuing.
Both men carried Irish passports. The Irish embassy. has been informed and is offering consular assistance.
Jimmy’s Place, with its bar and budget hotel, is situated close to the centre of Pattaya, a popular tourist destination on the east coast of Thailand.
The stabbing happened around 1.30am on Sunday, according to Thai police.
Eyewitnesses described how Mr Brennan was sitting on a stool by the bar when he was approached by another man holding a four-inch knife. He was then fatally stabbed. There was still blood on the floor of the bar by the stool.
Mr Brennan was taken to hospital but was pronounced dead on arrival.
Friends of Mr Brennan said he had only recently married his wife, who has a daughter aged five from an earlier relationship.