The 25-year-old from LaSalle, Ont., Finished in 2 minutes 5.42 seconds on Saturday – behind Kaylee McKeown (2: 04.68) and ahead of Emily Seebohm (2: 06.17), both Australians.
The Canadian women’s swimming team generated five medals in Tokyo, including the other silver in Mass in the 100-meter backstroke on Tuesday.
“I know I have high expectations of myself, but I’m really happy to be on the podium for a second time at the Olympics,” Masse said.
She has a chance of winning a third medal as she is expected to swim the backstroke of the women’s medley relay on Sunday.
Masse led 150 yards in the 200 but was caught on the wall by McKeown.
“I knew it was going to play out until the last moment,” Masse said. “I think maybe from what I was feeling my hitting frequency maybe slowed down a bit at the end.
“I’m going to have to come back to the race and talk to the coaches, but it was the best time for me, a Canadian record, so I have to be happy with that.
Masse’s Canadian teammate Taylor Ruck of Kelowna, BC, was sixth with a time of 2: 08.24.