At least he was in good company. American star Michael Phelps also failed to reach the podium on a busy day in the pool Saturday.
Cochrane missed out on the final of the men's 400-metre freestyle, finishing ninth in qualifying for the second Games in a row.
The Victoria native won his heat and appeared to have the eighth spot in the final locked up when South Korea's Park Tae-hwan was disqualified for a false start. But when South Korea appealed and Park was reinstated, Cochrane ended up out of the final by just one-hundredth of a second.
"Ryan is obviously not happy with the fact that he's not swimming the final, but he's also looking forward to getting ready for the 1,500 freestyle, his primary event," Canadian team coach Randy Bennett said at a news conference prior to the finals.
Park, the defending Olympic and world champion, went on to win silver in the final behind China's Sun Yang.
Phelps was denied his 17th Olympic medal when he finished fourth in the men's 400-metre individual medley.
"It was just a crappy race," Phelps said. "I felt fine the first 200, then I don't know. They just swam a better race than me, a smarter race than me, and were better prepared than me. That's why they're on the medal stand.
Phelps's American rival Ryan Lochte turned an anticipated showdown into a blowout, winning the race by more than three seconds. Brazil's Thiago Pereira took the silver, and Japan's Kosuke Hagino claimed the bronze.
It was the first time since the 2000 Sydney Olympics that Phelps failed to win a medal in an event where he reached the final.
Meanwhile, the first athlete to qualify for the London Olympics also won its first gold medal.
Yi Siling of China, who earned a shooting quota spot when she won the world women's 10-metre air rifle championship in Munich two years ago, claimed gold in the discipline in her Olympic debut.
"I feel like I had a lot of luck," said Yi, who trailed Poland's Sylwia Bogacka until the eighth of 10 shots.
Meanwhile, the London Games also produced a doping sanction just one day into competition. The International Olympic Committee banned Albanian weightlifter Hysen Pulaku after he tested positive for a banned steroid on July 23.
After one day of competition, China leads the medal standings with six (four gold, two bronze), followed by Italy (two goals, two silver, one bronze) and the United States (one gold, two silver, two bronze).
Canada is aiming for a top-12 finish at the Games and will have a couple of chances at a medal on Sunday.
Reigning World Cup silver medallists Emilie Heymans and Jennifer Abel team up in the women's three-metre diving synchro, while Clara Hughes attempts to become Canada's most decorated Olympian by reaching the podium in the women's road cycling race.