John O'Brien has been found not guilty of the murder of his wife Meg Walsh in 2006.
A jury of seven men and five women spent five hours and 20 minutes deliberating at the Central Criminal Court.
Mr O'Brien, of Ballinakill Downs in Waterford, had denied the murder of his wife on a date between 1 and 15 October 2006.
Mr O'Brien gave evidence in his own defence at the trial. He told the court he had no hand, act or part in his wife's murder.
After the not guilty verdict was announced, there was silence in the courtroom.
Mr O'Brien shook hands with his defence team and hugged his family afterwards.
Ouside the courtroom Meg Walsh's brother, James Walsh, read a statement on behalf of the family.
He said Meg was the last thing they thought about at night and the first thing in the morning.
He also said the State and the legal system had let them down miserably.
Mr Walsh said his family remembered Meg as a lovely woman; 'bubbly, happy and caring'.
The investigation into the murder of Ms Walsh was one of the largest garda investigations in recent years.
Thousands of people assisted in what was firstly a missing persons inquiry. A murder investigation was launched following the discovery of Ms Walsh's body in the River Suir on 15 October 2006.
She had been missing for two weeks.
More than 120 witnesses gave evidence during the trial, which lasted almost four weeks.
Ms Walsh was a mother of one; her daughter Sasha was 17 years old when her mother was killed.