Officials and residents reported serpentine queues in almost all the 11,763 polling stations as men and women - the elderly included - turned up in large numbers right from the time polling began at 7 a.m.
Within six hours, 40 percent of Delhi's 12 million electorate had voted. An Election Commission official said he expected record voting this time.
Voter enthusiasm was evident in both middle class and working class areas. In some places, the queues snaked out of the school buildings where polling stations were set up.
Even affluent localities, which are usually lethargic vis-a-vis elections, reported heavy polling.
A total of 150 candidates are in the fray in Delhi.
The Delhi battle is critical for the Congress, which won all seven Lok Sabha seats in 2009. It is equally important for the Bharatiya Janata Party (BJP) which has vowed to snatch all seven in order to ensure a BJP-led coalition government in New Delhi.
Delhi is also crucial for the Aam Aadmi Party, which has to prove that its support base has not eroded since its 49-day minority government went out of office Feb 14.
Among the early voters here were Vice President Hamid Ansari, Congress president Sonia Gandhi, her son and party vice president Rahul Gandhi, AAP leader Arvind Kejriwal and BJP's Harsh Vardhan, who is contesting from Chandni Chowk.
While Sonia and Rahul Gandhi did not talk to the media, Priyanka Gandhi, who came to vote with husband Robert Vadra, said there is "no Modi wave in the country".
On his part, Kejriwal said after casting his vote in Tilak Marg: "We are confident that we will win all the seven seats. We are sure that the youth and others will vote for us."
BJP candidate from New Delhi Meenakshi Lekhi, a lawyer by profession, said people were voting en masse for Narendra Modi, her party's prime ministerial candidate.
"Modi wave is a reality... both the rural and urban voters are with us," Lekhi told IANS.
With the emergence of the AAP, Delhi is witnessing a triangular fight in any Lok Sabha contest for the first time.
There are 7,057,648 male and 5,657,785 female voters besides 839 'others'.
Chief Electoral Officer Vijay Dev said Delhi will break all records in polling.
"I am sure a lot of people, including youth and women, will come out and vote," he said. In 2009, the voting percentage was 58.19.
Homemaker Paloma Ganguly said she was very excited to cast her vote.
"I was surprised to see so many people from resettlement colonies and shanties lined up. I never thought so many people will turn up so early," Ganguly told IANS.
Delhi's Lt Governor Najeeb Jung said after voting with his family. "We
must strengthen Indian democracy by exercising our right to vote," he said and urged citizens to vote without fear.