The 20-year-old fought his heart out last night but could not prevail over his stronger opponent who scripted a 23-18 victory to romp into the semifinals.
But the high-scoring result left the Indian contingent fuming as they claimed that the refereeing had gone heavily against the diminutive Manipuri who was warned once in the second round for head-butting his opponent.
With Devendro's exit, the Indian challenge in the boxing ring came to an end with only M C Mary Kom providing the spark with a historic bronze medal in women's boxing which was introduced in the Olympics for the first time.
Seven male boxers were in fray here, including 2008 Games bronze-medallist Vijender Singh (75kg), who also lost in the quarterfinals.
Backed by the packed arena, Barnes took an early lead by winning the first round 7-5 and maintained the tempo right through to send Devendro packing from of his debut Olympics much to the disappointment of the Indian fans.
Both the boxers started the contest aggressively unleashing a flurry of punches at each other but the Irish pugilist relied on his experience to gain the upperhand.
Trailing by two points, Devendro continued to be aggressive but a warning gave his opponent a bigger lead by the end of the second round which ended 10-5.
The third and final round saw both the boxers going all out and Devendro desperately tried to regain lost ground.Barnes, who had eked out a comfortable lead by then, was warned in the third round.
But Barnes ensured that he did not concede too many points.
The entire stadium, mostly filled up with Irish supporters, burst into cheers when Barnes was declared the winner.
Barnes will take on top seed Zhou Shiming of China in the semifinals on August 10. Zhou defeated Birzhan Zhakypov of Kazakhstan 13-10 in his quarterfinal bout.
The Indians were livid with the decision which they claimed had been extremely unfair on Devendro.
"There were so many mistakes against our boxers. He (Barnes) was not hitting the right spots and still getting points. It was not fair," India's Cuban coach B I Fernandez said after the bout.
"The refereeing was poor, not only in this bout but many other Indian bouts. It is very sad, but we have to live with it. The opponent was clearly holding, but he didn't say anything." Fernandez said.
On the mood in the Indian boxing camp, Fernandez said, "It's very difficult. We deserved to get a medal here."
National coach Gurbakhsh Singh Sandhu said some times referees get influenced by the crowd and Devendro was hit hard by that.
"Sometimes the referees go with the crowd. The referees use their own mind, I don't want to say too much on it"', he said.
On the performance of the Indian team, Sandhu said, "I am extremely happy with the overall performance of the Indian boxers. But I am very sad also because I think I am responsible for not being able to translate those performances into medal winning performances."
"We had come for medals. We are very grateful to Mary Kom who has come to our rescue and got a medal, he said.
Sandhu was, however, full of praise for Devendro who fought his heart out but was unlucky not to make it to the semifinal.
"He was aggressive right through. What else do you expect from such a young boxer. I am happy with his performance," Sandhu said.
Barnes was thrilled with his victory and said he was now looking forward to the semifinals.
"It is a dream come true to be here. I am over the moon. It was a real achievement. The fans make me proud to be Irish. Words can't describe how I am feeling," Barnes said.
"I knew he would come forward all guns blazing. It was really nerve wracking, but I dug deep and just got on with it, he said.
On meeting Shiming in the semifinal, he said, "Bronze medals are for losers. I am fighting a guy in the next fight who beat me 15-0 in Beijing. Our plan in the next fight is to score a point."
On becoming the first Irish boxer to win medals at successive Olympic Games, he said, "I don't really think about that. Just qualifying for the Olympics was a dream come true."