Ranomi Kromowidjojo of the Netherlands won the 50m freestyle to complete the women's sprint double at London 2012.
Britain's Fran Halsall missed a podium place by 0.08 seconds in fifth as Kromowidjojo clocked an Olympic-record 24.05 seconds.
Kromowidjojo adds the 50m title to the 100m freestyle she had already won.
Aliaksandra Herasimenia of Belarus took silver, Dutchwoman Marleen Veldhuis the bronze and defending champion Britta Steffen of Germany was fourth.
Halsall, who was sixth in the 100m event on Thursday, finished in 24.47 seconds. The 24.13 Halsall recorded at the British trials in March would have won her Olympic silver.
It means Great Britain have failed to achieve their target of six medals at London 2012.
Michael Jamieson's 200m breaststroke silver and two bronze medals for Rebecca Adlington are the team's only honours at the Games; although Keri-Anne Payne could increase that to four in next week's open water event.