Hermenegildo is a partner and heads the Energy and Utilities practice in Bird & Bird Spain.

He specialises in Energy Law, regularly advising on projects and transactions in Spain and Latin America, and has broad experience in investment protection and arbitration in Latin America.

Hermenegildo is considered by the main international law directories (Chambers & Partners) to be the top expert in foreign investment in Cuba, where he regularly advises some of the main market players in the energy (power, oil and gas), natural resources, aviation, agribusiness, tourism, food and infrastructure industries.

He formed part of the legal team which first designed the rules governing the electricity market in 1997. He has also advised private investors in conflicts relating to the energy industry in the Dominican Republic, Nicaragua and Cuba. He is currently participating in several investment arbitration proceedings pursuant to the Energy Charter Treaty.

He is co-director of the Energy and Regulation Forum of the foundation Fundación para la Investigación sobre el Derecho y la Empresa (FIDE), director of the Energy Law program at Instituto de Empresa (Madrid) and associate professor of Private International Law at Universidad Francisco de Vitoria (Madrid). Hermenegildo regularly takes part in the radio programme La Tertulia Capital on Capital Radio (103.2 FM).

He was awarded Best energy lawyer in Spain (Client Choice Award) by the International Law Office in 2010, 2011, 2013, 2014, 2015 and 2016. He was also voted Lawyer of the Year in 2012 and 2016 by Best Lawyers for the Natural Resources industry. In autumn 2012, Hermenegildo’s team was awarded Spanish Energy Law Firm of the Year by Acquisition International. In 2017 Hermenegildo's practice was awarded by Chambers & Partners Latin America as International Counsel in Cuba.