By 10 a.m. local time Sunday, voting had been proceeding at 333 constituencies in 68 Thai provinces, while 42 constituencies in nine provinces had canceled polling, the Election Commission said.
Sunday's voting will last till 3 p.m., with a total of 93,305 polling stations set up in 375 constituencies nationwide for 48.77 million eligible voters.
Around 130,000 police officers, along with several thousand soldiers, have been deployed nationwide to maintain order at polling stations.
On Sunday morning, caretaker Prime Minister Yingluck Shinawatra cast her vote at a polling station near her residence in the capital Bangkok. No protesters were rallying there to block her voting.
Election Commissioner Somchai Srisuthiyakorn failed to cast his vote as no election officials turned up at his polling station, which was later announced closed.
Anti-government protesters have blocked several roads in the capital as part of the operation to completely shut down the city to prevent voting, which was earlier proposed by protest leader Suthep Thaugsuban. Endi