Our Firm


Having its origins in the respected and traditional industrial property agency Momsen, Leonardos & Cia, our firm has inherited an invaluable legacy: highly-qualified practitioners and the experience of 100 years of history in the provision of services to register and protect the industrial and intellectual property rights of some of the largest and most important companies in the world, from the most diverse industries.

We accompany the growth of Intellectual Property activities in our country, which gives our expertise an advantage in the practice of this area of Law

A worth remembering history

In 1919, the American lawyer Richard P. Momsen founded his Law firm in Rio de Janeiro, which later became Momsen & Harris. Simeon W. Harris, its first partner, was descended from American immigrants who arrived in Brazil following the American Civil War. In 1927, Thomas O. Leonardos joined the firm, which in 1944 adopted the name Momsen, Leonardos & Cia.

At the end of the 1950s, a second generation of partners entered the firm. Tomaz Francisco Leonardos and his brothers, together with Carlos Henrique Fróes and Walter Pinho, consolidated the standards of excellence, throughout years of service, for which the firm had become known.

During the 90s, the firm received a new generation of partners. Filipe and Gabriel, representing a third generation of the Leonardos family, together with Elisabeth Kasznar Fekete, started to practice in the Trademark Department. At the same time, Denise Dale, daughter of José Maciel de Oliveira, became partner of our Patent Department. Some years later, Gustavo Barbosa, Eduardo Rosman and João Luís Vianna joined Denise as partners responsible for the Patent Department.

With expertise recognised in Brazil and abroad, Momsen, Leonardos & Cia has been named for four consecutive years in the annual of Brazilian magazine Análise Advocacia, as one of the three most admired firms in the country in the Intellectual Property field.


about us

Invaluable legacy

One of the founders of Momsen, Leonardos & Cia, Thomas Othon Leonardos (1906-1990) is the father of consultant at Kasznar Leonardos, Maurício Leonardos, and of ex-consultant Tomaz Francisco Leonardos.

Thomas Otton was the grandfather of lawyers Gabriel and Filipe Leonardos. Click here to read an article written by the renowned academic Aurélio de Lyra Tavares about Thomas Othon Leonardos, published in the Jornal do Commercio in 1990.

There is another beautiful text that reveals a little more about the great man and great jurist Thomas Othon Leonardos. To celebrate Thomas’s 80th birthday, his colleague Ives de Oliveira, from the Institute of Brazilian Lawyers, paid homage to him in a speech. Click here to read the document in full.

Today, 26 years after the death of Thomas, his grandsons and other partners continue to leave the firm’s mark on the history of the field of intellectual property.


The quality and experience of our practitioners, allied to the ethical and multidisciplinary nature of our team, form our great competitive edge.



MIP IP Stars
Top Ranked - Chambers Brazil 2021
Guia WRT 1000
Leaders League
Top Ranked - Latin America Chambers 2019
Guia Iam 1000
IP Stars Ranked Firm
Top Ranked - Global Chambers 2019
Guia The Legal 500 LA
Latin Lawyer 250