George Osborne has said he is hopeful of a "win-win" agreement between the UK and the rest of the European Union in talks over its future membership.
Speaking in Paris as he met French counterparts, the chancellor said there was "goodwill and a willingness to engage" with British arguments.
But he would not be drawn on reports a referendum could be brought forward to 2016 if negotiations concluded quickly.
Mr Osborne is planning to visit other EU capitals in the coming months.
His visit came as UK universities launched their campaign for a "Yes" vote in a future in-out referendum, scheduled to take place before the end of 2017.
Mr Osborne, who is holding meetings with French Economy Minister Emmanuel Macron, its Finance Minister Michel Sapin and Foreign Minister Laurent Fabius, said all sides "wanted to get on and talk".
Analysis, by BBC Paris correspondent Lucy Williamson
After all the talk of roadblocks and differences, today's meeting had a rather different feel. Both Mr Osborne and Mr Macron talked about "a win-win approach" on Britain's proposed reforms of the EU.
We want a Europe that works for all its citizens, said the chancellor, adding that France agreed the interests of non-eurozone countries like Britain should be protected.
His French host was keen to emphasise the need for reform. The warnings against an "a la carte" Europe were gone. "I think we have the basis of a common agreement," Mr Macron said. "France wants reform that strengthens Europe, not reform that weakens it. But I've heard nothing today that was incompatible with that."
The devil, of course, will be in the detail of those reforms. Asked about a timetable for the British referendum, Mr Osborne didn't rule out holding it early. But broad agreement on the need for reform is one thing, getting 28 countries to sign up to specific measures quite another.
He told the BBC: "I don't know anyone claiming the negotiations are going to be straightforward but you hear a lot of goodwill here and a willingness to engage because we all want to see Europe working better for the citizens of the entire EU.
"And now you hear French politicians acknowledging there needs to be fair treatment for those countries that aren't in the euro as the eurozone integrates and there is the potential for a win-win agreement."
Mr Osborne's visit marks a new phase in the negotiating process, in which the technical detail of the UK's requests are being considered.
David Cameron, who visited Paris, Berlin and other EU capitals in the wake of May's election victory to set out his government's broad objectives, said the discussions were "proceeding quite well, but there'll be lots of difficulties and problems and road blocks ahead to get the sort of deal I think is necessary".
Speaking in Indonesia, where he is on a trade trip, Mr Cameron said he did not have a referendum date in mind, amid reports that ministers favoured next June: "When the negotiation is complete then we'll set the date for the referendum," he said.
What does renegotiation mean?
The prime minister has not set out in full detail what he wants but his key demands include:
- An opt-out on the core EU aim of "ever closer union"
- The sovereignty of national parliaments to be boosted, so groups of them can block proposed EU legislation
- Safeguard the City of London and other financial centres outside the eurozone
- Curb EU immigration by cutting benefits
- Make the EU more streamlined and competitive
To get what it wants the UK believes it will need to rewrite treaties agreed by all 28 EU members.
Meanwhile, the Universities UK group - whose members include 133 executive heads of UK university institutions - has said it backs Britain's membership of the EU. Vice-chancellors launched a "Yes" campaign alongside shadow business secretary Chuka Umunna and pro-European Tory MP Damian Green.
Dame Julia Goodfellow, president of Universities UK, told the event in London they must "stand up and be counted".
"It is abundantly clear that the UK's membership of the European Union has an overwhelmingly positive impact on our world-leading universities, enhancing university research and teaching," she said.
"The case for staying in Europe is about ensuring the future prosperity of the UK, it's about maximising the chances of new discoveries that enhance the society in which we live, it's about the UK's standing in the world."
UKIP, which is campaigning for a "No" vote in the referendum, criticised Universities UK for entering the debate.
Deputy leader Paul Nuttall, an MEP and former university lecturer, said: "Given that universities are supposed to be the bastions of open-minded learning, it seems wrong that an institution governing the interests of British education should embroil itself in a political debate that has seen people denied any democratic say whatsoever on how Britain should be governed for 40 years."
And Conservative eurosceptic John Redwood said attempts to present a Yes vote as the "friendly status quo" were misleading.
"They aim to run a campaign claiming that... Yes is the risk free option, and that No would mean all sorts of dire futures which they intend to portray by lies and scare stories," he wrote on his blog.