Debentures find their most distant roots in the category of obligations arising from a unilateral declaration of will, since, in effect, the security itself is a unilateral promise of payment.
The practice of borrowing from the public by creating an obligation dates back to the Middle Ages, and emerged in Public Law as a tactic used by the monarch to obtain resources for certain undertakings, including financing wars.
Rubens Requião notes, citing Jean Escarra, that the Republic of Genoa, since the 12th century, had been issuing loans guaranteed by the collection of certain taxes, and that, according to Machiavelli, these loans, in the 14th century, began to be divided into fractions of equal value, as in the famous case of the group of creditors who came together in a corporation called Casa de San Giorgio, closely resembling modern associations of debenture holders.
The adoption of debentures in the private sector, as an instrument of the business world, only occurred in the 19th century, during the Industrial Revolution, and emerged precisely in England, where the word debenture was first used in this sense.
As Waldemar Ferreira points out, the word has Latin origins (debeo, debentur mihi), having appeared in the English language with different meanings until it crystallized, around 1862, in its current meaning, becoming widespread in the City, and then throughout the world.
The Brazilian Commercial Code, which was enacted in 1850, naturally made no reference to debentures. Law No. 3,150, of November 4, 1882, when regulating corporations, provided for the contracting of loans through the issuance of bearer bonds. However, the regulation of this law referred to debentures as synonymous with bearer bonds. Subsequent laws continued to adopt this dual terminology until the current law on corporations (Law 6,404/76), which definitively settled on the term debenture.