Speaking to reporters on Tuesday, Head of the Atomic Energy Organization of Iran (AEOI) Ali Akbar Salehi said the country sent the cargo of heavy water to Oman after the other parties to the JCPOA expressed readiness to purchase the product.
Heavy water is used in some nuclear reactors, but is not radioactive.
Under the JCPOA, which came into force in January, Iran is allowed to use heavy water in its modified Arak nuclear reactor, but should sell any excess supply of both heavy water and enriched uranium on the international market.
In April, the US Department of Energy, or DOE, confirmed plans to buy 32 metric tons of heavy water from Iran worth $8.6 million.