Cristina Gallach, a spokeswoman for Solana, said the meeting was expected to run for about three hours and it was hoped there would be a statement afterwards.
The Solana-Larijani encounter was originally scheduled for Wednesday but was postponed at the last minute.
The meeting began at 5.00 pm local time.
A Vienna-based diplomat said that the problem in getting Larijani and Solana together was because they wanted to be sure that there would be a [good] outcome before they go into the meeting.
The meeting comes at a time when the US wants a UN Security Council resolution on imposing sanctions on Iran over its contested nuclear programme to be drafted as early as next week.
Nicholas Burns, the US undersecretary of state, said on Friday in Berlin that the outcome of the talks would allow six major nations trying to win guarantees that Iran would not make nuclear weapons to complete a sanctions resolution when they meet in New York at the UN General Assembly the week after next.
"I'm sure that the conversations or discussions will be difficult, otherwise the matter would have been resolved months ago. But we have to go into this making every effort in order to succeed"
EU foreign policy chief
The six - including Russia and China - are seeking talks with Iran on a package of benefits for the Islamic Republic but demand that Tehran first suspend uranium enrichment, which makes nuclear power reactor fuel but can also produce atom bomb material.
Iran claims that it has a right to what it says is peaceful nuclear work to generate electricity.
Solana had said in Copenhagen on Friday that it would become clearer on Saturday whether it would be possible to begin negotiations between Tehran and the six world powers.
"I'm sure that the conversations or discussions will be difficult, otherwise the matter would have been resolved months ago. But we have to go into this making every effort in order to succeed," Solana said.
An Irainain diplomat told Reuters: "On Saturday [Iran] will be testing the goodwill of the EU side to go in the right direction, a peaceful solution without preconditions.
"They are serious and hope the [EU] side shows a similar seriousness. They are ready to discuss all the questions important to both sides and remove the ambiguities."
Solana said that he was optimistic but not naive about the outcome of talks with Larijani.