Brazil and Argentina are in early talks to establish a shared unit of value for bilateral trade to reduce reliance on the US dollar, Brazilian President Luiz Inacio Lula da Silva said.
The move is not, however, aimed at replacing existing currencies.
In Buenos Aires on his first international visit since taking office, Lula made the comments alongside Argentine President Alberto Fernandez, who said there was little decided about what would be involved in such a proposal.
The discussions surfaced as part of an agreement to boost bilateral trade with more Brazilian export financing backed by Argentina's international collateral.
Argentina's economy is suffering from a series of challenges, including a lack of dollars, with the government battling to replenish foreign currency reserves while also grappling with an inflation rate of nearly 100% last year.
Leaders from both countries are meeting at a regional summit in the Argentine capital.
There Lula vowed to resume a closer relationship after former Brazilian president Jair Bolsonaro distanced himself from Argentina.
"Our finance ministers, each with his own economic team, can make us a proposal for foreign trade and transactions between the two countries that is done in a common currency," Lula said alongside Fernandez.
Fernandez said that he and Lula also discussed the possibility of shipping gas from Argentina's Vaca Muerta shale formation to its neighbour.
Brazil's development bank BNDES may finance the building of a pipeline to deliver the gas, Lula said.
Brazil's Finance Executive Secretary, Gabriel Galipolo, told Reuters that the currency, or "regional unit of account," would come alongside extra credit to support exports to Argentina through Brazilian banks that operate locally.
Brazil's government would offer guarantees to banks that helped provide financing, while Argentina, a major grains exporter, would have to provide collateral via hard assets like grains, gas or oil.
Under the plan, the Brazilian real and Argentine peso would continue to exist, with the new tender targeted narrowly at trade.
Brazil's Finance Minister Fernando Haddad said the presidents of both countries requested the creation of a clearing house with a common currency to settle accounts.
The currency has no name or deadline and would not seek euro-style monetary unification, he added.