Oscar Romero died on 24 March 1980, aged 62, after being shot during his sermon in the capital, San Salvador.
He was an outspoken critic of the military regime during the country's civil war and had denounced the oppression of the poor and the 'right-wing death squads' in Guatemala.
His martyrdom was initially blocked by the Catholic Church because of concerns that he had Marxist ideas.
But after Pope Francis' election in 2013 the sainthood process was allowed to get underway.
A note from the Vatican confirmed the "martyrdom of Servant of God Oscar Arnolfo Romero Galdámez, Archbishop of San Salvador ... killed, in hatred of the faith, March 24, 1980, in San Salvador."
It now means Oscar Romero will be beatified - the first step to sainthood.
For him to become a saint a miracle will have to be attributed to him.
No one was ever convicted of the archbishop's murder.