Voting began at 6 a.m. and is due to end at 5 p.m., with the estimated results expected to be released shortly after, reports Efe news.
However, due to the record one million applications for vote by mail, the results will in principle be missing up to 20 per cent of the total ballots, meaning that the final result will only be declared by Monday.
The polls give former Chancellor Sebastian Kurz's party up to 35 per cent of the votes - 3.5 per cent more than it earned in the October 2017 general elections - which would give it 65 of the 183 seats of the Nationalrat, the lower house of Parliament.
Kurz was toppled from the Chancellery in May after just 525 days in office with the eruption of a corruption scandal involving the leader of his government's coalition partner, the Freedom Party (FPÖ), which collapsed the coalition and led to a no-confidence motion.
According to the polls, the FPÖ could lose six points and be left with 20 per cent of the votes and 38 MPs, moderately affected by the fact that its leader until May, Heinz-Christian Strache, is being investigated for embezzlement.
The polls predict that the Social Democratic Party (SPÖ), led by Pamela Rendi-Wagner, will have its worst showing in history with 22 per cent of the vote and 42 lawmakers, five points less and 10 fewer seats than two years ago.
Tipped to finish fourth is the Greens party, which is expected to make a triumphant return to Parliament with up to 24 representatives.
The party, which failed to reach the minimum 4 per cent needed for parliamentary representation in 2017, could now obtain up to 13 per cent of the votes, driven by the growing importance of the environmental and climate debate.
Liberal party Neos is expected to surpass its 2017 results and go from 10 to 15 lawmakers.
If these results were confirmed, Kurz could opt for a coalition with the Greens and Neos instead of the FPÖ, with whom he shares a virulent anti-immigration stance.
( With inputs from IANS )