Barthélémy is Counsel in Gide's "Projects" (Finance & Infrastructure) team in New York . He has headed the Projects practice in the New York office since 2022. He specialises in the development of infrastructure projects in Africa, the Middle East and the Caribbean.

Barthélémy advises financial institutions (World Bank, EBRD, IDB, etc.), development agencies (USAID, AFD, etc.) and contracting authorities on the structuring and implementation of these projects. He also advises the companies that build and operate these infrastructures and the lenders that finance them. His preferred sectors are energy, water, transport and mining projects.

Barthélémy has worked with clients in Tunisia (sanitation), Botswana (water), Malawi (irrigation), Benin (water), Madagascar (energy), Mali (energy), Burkina Faso (energy), Guinea (mining), Gabon (mining, railways), Jordan (water, energy, transport), Jamaica (water, roads), Haiti (energy, port, industrial park), Belize (energy), Ukraine (ports), Kazakhstan (road, energy), Mongolia (energy), Maldives (airport), Solomon Islands (energy).

Barthélemy completed his internships at Linklaters, Shearman & Sterling, EDF and Qatar, as well as a secondment at ContourGlobal. He holds a master's degree in private law from Lyon II and is a graduate of IEP Lyon with a specialisation in "PPP Engineering". He also studied at the University of Pennsylvania and Harvard University, and has been a member of the Paris Bar since 2013.