"This election is crucial for our country. It will lead our country to full democratic rule," commission chairman Apichart Sukhagganond told the assembled party leaders.
He said he wanted to offer assurances that the commission was neutral throughout the campaign.
Parties have until Sunday to register candidates who will contest 80 party list seats in parliament, which are voted for according to regional zones.
Registration opens on Monday for candidates contesting 400 constituency seats.
'Free and fair'
The military junta behind last year's coup and the civilian government it appointed have promised that the election will bring a full return to democracy in Thailand, more than a year after the bloodless coup that removed Thaksin from power.
|Thaksin still has strong support |
among many Thais [EPA]
They have insisted the vote will be free and fair, but analysts have expressed doubts over the pledge as about a third of the country remains under martial law.
In addition Thaksin's Thai Rak Thai party, which stormed the polls in 2001 and 2005, has been dissolved.
The vote will also be Thailand's first under a new constitution which was approved in a referendum in August.
Pro-democracy activists have criticised the charter saying the new rules set Thailand up for a weak coalition government while returning real authority to the traditional power centres of the military, the bureaucracy and the royal palace.
Whoever eventually forms the new government will face several challenges, not least of which is a sagging economy with confidence dented since the coup.
They will also have to deal with the ongoing conflict in the country's south, and lingering divisions over coup itself.
Thaksin, the former prime minister and now living in exile, was accused of massive corruption and abuse of power.