Bartolomeu Lourenço de Gusmão (December 1685 – 18 November 1724) was a Portuguese priest and naturalist from Colonial Brazil who was a pioneer of lighter-than-air aerostat design, being among the first scholars at that time to understand the operational principles of the hot air balloon and to build a functional prototype of such device.

It is known that Gusmão was working on this principle at the public exhibition he gave before the Court on 8 August 1709, in the hall of the Casa da Índia in Lisbon, when he propelled a small balloon to the roof using combustion from a flame.

His designs included a ship to sail in the air consisting of a triangular gas-filled pyramid, but he died without making progress.One account of Gusmão's work suggests that the Portuguese Inquisition forbade him to continue his aeronautic investigations and persecuted him because of them, but this is probably a later invention.

The inventor proposed to make new experiments, but, chagrined at the raillery of the common people, who called him wizzard, and terrified by the Inquisition, he took the advice of his friends, burned his manuscripts, disguised himself, and fled to Spain, where he soon after died in an hospital.

They add, that several learned men, French and English, who had been at Lisbon to verify the fact, had made enquiries at the Carmelite monastery, where Gusmao had a brother, who had preserved some of his manuscripts on the manner of constructing aerostatic machines.