It is the second meeting during the ongoing negotiations and before the joint JCPOA meeting.
Iran's top negotiator Ali Bagheri Kani at the head of a delegation arrived in the Austrian capital on Monday for following up the eighth round of talks aiming to remove unjust sanctions.
The JCPOA Joint Commission meeting will be held at the level of heads of negotiating delegations between Iran, the European Union (EU), and 4+1 this afternoon.
Negotiators reached the agreement after three-week-long talks in the previous round of talks and long-term denial of Iran's legitimate demands from three European states.
The agreement was on the joint text and based on the continuation of negotiations in which Iran's demands have been taken into consideration.
During the fresh round of talks, the sides are to exchange views about the contents of the text and road map for the revival of the July 2015 nuclear deal, aka JCPOA.