– November 2022 – Ongoing: Ambassador and Head of Delegation of the European Union to the United Kingdom
– December 2019 – October 2022: Head of Cabinet of High Representative for Common and Security Policy and Vice President of the Commission
– November 2015 – November 2019: Deputy Secretary General for Security and Defence Policy and for Crisis Response in the EEAS
– September–October 2015: Principal Adviser for “Crisis Response and Operational Coordination” to the Secretary General, EEAS, European External Action Service
– December 2014 – September 2015: Managing Director a.i., Crisis Response and Operational Coordination, EEAS, European External Action Service
– July 2012 – November 2014: Principal Adviser on External Affairs, Cabinet of the President of the European Council
– January 2012 – June 2012: Director for South and South-East Asia, EEAS European External Action Service, Brussels
– January 2010 – October 2011: Ambassador, Acting Head of the EU Delegation to UN, New York
– August 2007 – December 2009: Ambassador, Head of the Liaison Office of the Secretariat of the Council of the European Union to UN, New York
– April 2005 – July 2007: Director for Civilian Crisis Management, General Secretariat the Council of the European Union, Brussels
– September 2003 – March 2005: Deputy Head of Cabinet High Representative for Common Foreign and Security Policy of the EU, Brussels
– August 2000- August 2003: Counsellor in the Permanent Representation of Spain to the European Union, Brussels
– December 1998 – July 2000: Deputy Head of Mission, Embassy of Spain in Cuba
– September 1996 – November 1998: Deputy Director General for UN, Ministry of Foreign Affairs of Spain, Madrid
– September 1993 – August 1996: Consul of Spain in Frankfurt (Germany)
– September 1989 – August 1993: Counsellor, Permanent Representation of Spain to the UN, New York
– August 1987 – August 1989: First Secretary, Embassy of Spain in United Republic of Tanzania
– November 1985 – July 1987: Second Secretary, Eastern European and CSCE Affairs, Minister of Foreign Affairs of Spain, Madrid
– September 1985 – October 1985: Joined the Spanish Diplomatic career

He has a degree in law from Universidad Complutense Madrid.
He is a Spanish national, EU Official and Spanish Career Diplomat.
Mr. Serrano has published numerous articles on EU security and defence policy as well as on EU foreign policy. He participates regularly in public events on such topics.