On her second Olympics in Beijing 2008, Kosti swam the individual freestyle double with only two days in between. Leading up to the Games, she cleared FINA B-standard entry times of 56.30 (100 m freestyle) at Nioveia Grand Prix in Thessaloniki, and topped the field with 2:00.97 (200 m freestyle) at the Greek national trials in Athens. On the third night of the competition, she closed out the field to last place and forty-fourth overall in heat three of the 200 m freestyle, finishing with a time of 2:04.55. Two days later, in the 100 m freestyle, Kosti escaped from the bottom of the field to finish heat three in seventh position and thirty-seventh overall with a time of 56.44, edging out Slovenia's Nina Sovinek by almost a full second.