Due to be held in Vienna’s Palais Coburg hotel, the deputy-level talks are expected to run until Friday.
Iranian top negotiators and deputies to foreign minister, Abbas Araqchi and Majid Takht Ravanchi, are scheduled to hold talks with European Union Deputy Foreign Policy Chief Helga Schmid.
The EU coordinates diplomacy with Iran on behalf of the Group 5+1 (Russia, China, France, US, Britain, and Germany).
Expert meetings are also planned concurrent with the deputy-level talks.
Iranian Foreign Ministry's Director General for the Political and International Affairs Hamid Baeidinejad will head the country’s team of experts in the upcoming sessions.
Iran and the six powers have held several rounds of talks in recent months to hammer out a lasting accord that would end more than a decade of impasse over Tehran's civilian nuclear program.
On April 2, Iran and the sextet reached a framework nuclear agreement in Lausanne, Switzerland, with both sides committed to push for a final deal, known as the Joint Comprehensive Plan of Action (JCPOA), until the end of June.