20 Pesos

Banco Nacional de las Provincias Unidas del Río de la Plata was established in 1826 under the Rivadavia administration — itself a short-lived experiment in centralized liberal governance that collapsed within two years. The bank's notes were issued against a specie reserve that proved far thinner than advertised, and convertibility was suspended almost immediately after the 1826 war with Brazil strained public finances beyond recovery.

By 1836 the bank was liquidated entirely. Notes from this series circulated through a period of chronic depreciation, which means genuinely uncirculated survivors are exceptional rarities today.