There was also heavy balloting in Lucknow, the ailing Atal Bihari Vajpayee's former constituency where the BJP's candidate now is its chief, Rajnath Singh.
After casting his vote in Gandhinagar, Modi flew to Bihar where he addressed a huge rally in Ujiyarpur Lok Sabha constituency calling for "a strong government in the country".
"It is certain a new government led by the BJP will be formed," he said, predicting a defeat for the Congress-led UPA government.
But before that, Modi ran into trouble with the Election Commission after he flashed a badge of the BJP's election symbol "lotus" while addressing a press conference in Gandhinagar.
Amid protests by the Congress and the Aam Aadmi Party (AAP), the Election Commission ordered the Gujarat authorities to file a First Information Report against Modi and the electronic media that showed him flashing the "lotus" near the polling booth -- in violation of election laws.