"A decisive vote will be held on October 1, we will respect the vote," Catalonia's President Carles Puigdemont told a press conference.
Gabriela Serra, a member of the separatist coalition that governs Catalonia, said that if a majority of voters back the creation of a Catalan republic "obviously independence will have to be declared immediately".
If the "no" wins in the planned Oct 1 referendum, she added in Barcelona, new regional elections will be called.
The comments came as the coalition presented a bill aimed at extracting the northeastern region from Spain's legal system in a bid to circumvent all legal and practical challenges to organising a referendum - a move that will deepen tensions with Madrid.
The bill will be submitted to a vote in the Catalan regional parliament, where separatists hold a majority, at the end of August.
'COUP D'ETAT'
Lluis Corominas, another regional lawmaker from the coalition, announced the law would "prevail" over other rules in place.
Article 2 of the bill stipulates that the Catalan population is a "sovereign subject" that has the right to decide its own "political conditions".
But Xavier Garcia Albiol, head of Prime Minister Mariano Rajoy's conservative Popular Party in Catalonia, said it was merely "a coup d'etat dressed up as democracy".
Catalonia, a wealthy region of 7.5 million inhabitants with its own language and customs, has long demanded greater autonomy.
For years separatist politicians in the region have tried to win approval from Spain's central government to hold a vote similar to Scotland's 2014 independence referendum from Britain - which was approved by London - and resulted in a "no" vote.
But Madrid has remained steadfast in its opposition to such a vote, considering it a threat to Spain's unity, and this time is no different.
The Constitutional Court has already quashed a resolution approved by Catalonia's parliament calling for the referendum to take place.
It has also warned Catalonia's elected officials that they will face legal consequences if they take any steps towards holding such a vote.
The draft bill unveiled on Tuesday confirmed the date of the referendum, as well as the question: "Do you want Catalonia to be an independent state in the form of a republic."
DIVISIONS AMONG SEPARATISTS
But challenges from Madrid aside, Catalans themselves are divided on the issue.
Some 48.5 per cent are against independence and 44.3 per cent are in favour, according to a recent regional government poll - although a large majority want a referendum to take place to settle the matter once and for all.
On top of this, the Catalan executive has been wracked by internal debate over the issue, unable to find a way to guarantee the credibility of such a vote, if it ever manages to hold it faced with Madrid's refusal.
It has no regional election authority to oversee the vote, for instance, and has not found any companies willing to provide ballot boxes.
Aside from the legal bans of the Constitutional Court, the central government has also threatened civil servants with sanctions if they help organise the referendum, and has warned companies against any involvement.
In an interview on Monday, Jordi Baiget, the regional councillor in charge of business, expressed doubt over whether the referendum could take place, given the power of Madrid.
But this was not to the liking of Catalonia's President Carles Puigdemont, who promptly announced Baiget's departure on Monday evening - a decision that was criticised by some of the most fervent supporters of independence.
