The National record holder clocked a season's best time of 2:00.58 seconds but finished sixth in Heat 3 and 29th overall out of 65 runners.
The 27-year-old Indian clocked a season's best time of 2:00.58 seconds but finished sixth in Heat 3 and 29th overall out of 65 runners.
She holds the National record of 1:59.17 seconds, which she set in 2010.
She led the field for the first 600 metres but ran out of steam in the final stretch and saw her second Olympics campaign end in disappointment.
Only the top two finishers in each of the eight heats, and the next best eight runners, qualified for the semi-finals.
2015 World Championships silver medallist Melissa Bishop of Canada topped the heats with a timing of 1:58.39s, followed by reigning World champion Marina Arzamasova (1:58.44s) of Belarus and Habitum Alemu (1:58.99s) of Ethiopia.
With Luka's flop show, India's disappointment in track and field continued at the Games.
Only Lalita Babar made it to the final, in the women's steeplechase.
Luka, a protege of track legend P T Usha, has rarely done well on the global stage since making it to the senior level in 2009. She has done well only at the continental level, having won a bronze and silver in the 2010 and 2014 Asian Games respectively.
Her best performance is a sixth-place finish in the 2010 Delhi Commonwealth Games.
Luka was 15th in the semi-finals at the 2011 World Championships, 11th in the semis in the 2012 London Olympics, 15th in the heats at the 2013 World Championships, 11th in the semis at the 2014 Commonwealth Games and 19th in the heats at the 2015 World Championships.
IMAGE: Tintu Luka
Photograph: PTI