Manchester United boss Mourinho was interviewed for the post in 2008, after leaving Chelsea the previous year.
However, despite impressing Nou Camp chiefs and having emotional ties with the Catalan giants, Barcelona opted to go for Pep Guardiola instead.
Not much is known about why the 54-year-old was overlooked, particularly given the fact that Guardiola was a managerial novice at the time.
And Jose Mourinho has admitted to keeping his cards close to his chest about why he was never trusted with the Barcelona job.
“Maybe I will reveal the truth one day. There is something about my career that I want to keep secret,” he said.
“I will tell the truth when I will be really, really, really old.”
Speaking last year, Spanish football expert Pete Jenson claimed that the Barcelona job was the reason for Mourinho and Guardiola’s disliking of each other.
“It starts when the Barcelona job becomes available, and that’s clearly Jose Mourinho’s dream going back to the Nou Camp as the number one,” he said.
“He plans to appoint Guardiola as his number two, and it seems that he’s got the job.
“The decision is practically made, and Joan Laporta who was the president at the time had pretty much made up his mind.
“In the final hour, there are a few voices who say ‘maybe we should think about Guardiola. He’s just got the B team promoted.”
Mourinho worked at Barcelona in the 1990s as a translator for then-manager Sir Bobby Robson, with Guardiola part of the club’s playing staff at the time.
But it appears even that was not enough for him to be given the role he craved.
Barcelona chief executive at the time Ferran Soriano said he went for Guardiola because of the Spaniard’s history.
“Both had great virtues and they seemed to be at opposite ends of an imaginary scale,” he said.
“At the one end we had an experienced coach, who was successful, with a strong personality, and a controversial reputation.
“At the other end was a very talented person, who was totally familiar with the club, but without significant experience as a coach.”
In 2011, Barcelona legend Johan Cruyff said that, though the club went for Guardiola, Nou Camp president at the time Sandro Rossell wanted Mourinho instead.
“The worst thing is that Mourinho was favoured to take the Barcelona job by Rosell,” he said.
“I told him at the time that Guardiola was the best choice for me.”
