The defensive midfielder moved to Valencia in July 2012, having become surplus to requirements at Real Madrid.
But the Boca chief confirmed to Radio 9 that the Argentinian club are set to test the resolve of the Liga outfit having made a formal offer early in the January transfer window.
"We made a proposal to Fernando that we have not had answered yet," Martucci said.
"Gago expressed his willingness to return and now we must pass this [to the] leaders of Valencia."
The Argentina international made 69 appearances for Boca from 2004-07 before he moved to Santiago Bernabeu for an estimated €20 million fee.
The Blancos eventually sold Gago to the Mestalla last summer for €3.5m, five years after his arrival and having seen Roma - where he spent the 2011-12 campaign on loan - pass up on the option to buy him.