The much-awaited Gujarat electoral battle will take place Dec 13 and 17 while Himachal Pradesh will vote Nov 4 in virtual straight fights between the ruling BJP and the Congress.
Chief Election Commissioner V.S. Sampath said Wednesday that 37.8 million voters would be eligible to pick a 182-seat house in Gujarat. Himachal Pradesh has a 68-member assembly and 4.5 million voters.
The results will be out Dec 20.
The Gujarat outcome is widely tipped to have an impact on the political future of Chief Minister Narendra Modi and the Bharatiya Janata Party with the next Lok Sabha election due in 2014.
His supporters say that Modi, who was appointed chief minister in 2001, would be a strong contender for the party's prime ministerial candidate if he leads the BJP to power for a third time in a row.
A defeat will be a setback both for the BJP and Modi, puncturing his claims for a national leadership.
These will be the most important state elections since Uttar Pradesh, India's most populous state, voted in February-March this year, along with Goa, Punjab, Uttarakhand and Manipur.
Both states are ruled by the BJP, with the Congress desperate to dislodge it.
The announcement came hours after Congress president Sonia Gandhi unleashed her party's electoral campaign in Gujarat with a stinging attack on the BJP. But she avoided any mention of Modi.
The Congress welcomed the polls but quickly added that these would not be a referendum on Prime Minister Manmohan Singh's government.
"Every election is a local election, even parliamentary elections are decided by local issues. No state poll is a referendum on the performance of the national government," Congress spokesperson Manish Tewari said.
BJP spokesperson Rajiv Pratap Rudy said: "We are sure of victory in the two states."
Sampath detailed the steps taken by the Election Commission to ensure a transparent and peaceful ballot.
"We are making foolproof security arrangements in both states by deploying adequate strength of central police forces," said Sampath.
Sampath said there would be strict monitoring of expenditure by political parties and candidates as well as of "paid news".
All candidates would be required to open separate bank accounts and incur expenditure only from these accounts.
The Election Commission, Sampath said, expects "the highest standards" of conduct and neutrality from officials.
"Their work will be under constant watch and scrutiny," he said. The model code of conduct for political parties will be strictly enforced.
Sampath said the polling dates were determined after studying climatic condition particularly in Himachal, academic calendar, festivals, law and order, and availability of security forces.
Gujarat will have 44,496 polling booths and Himachal 7,252.
All candidates will file a single affidavit regarding their criminal past, if any, as well as their assets and educational qualifications.
In Himachal Pradesh, the poll notification will be out Oct 10 and the last date for withdrawal of nominations will be Oct 20.
In Gujarat, the notification for the two phases will be issued Nov 17 and 23. The last date for withdrawal of nominations will be Nov 28 and Dec 3.
In Shimla, Himachal Pradesh Chief Minister Prem Kumar Dhumal told IANS that the BJP would seek a positive verdict from voters.
He said development of the hill state despite discrimination by the Congress-led UPA government would be the main election plank. "We have lots of achievements to our credit."
The world's highest polling booth will be in Himachal, at Hikkam at over 15,000 feet in Lahaul and Spiti district. It has some 300 voters.
Sampath identified the oldest voter as 95-year-old Shyam Saran of Kalpa in Kinnaur in Himachal. Saran had voted in 1951 too.