The lead ship of the class was named after Rosario, one of the major cities in Argentina.

[citation needed] Argentina decided the construction of new warships due to the deterioration of relations with Brazil, who was after the naval supremacy in South America.

The Brazilian Navy ordered riverine monitors to patrol the border rivers; Argentina's response was to place a contract with the British shipyard Armstrong, Mitchell & Co for the construction of two riverine gunboats.

[1] The Rosario class gunboats had a shallow draft metal hull with a single mast and funnel on the superstructure amidships.

They were powered by two Vickers triple-expansion steam engines fed by two Yarrow boilers, driving two propellers.