[5] In August 1983, Neuhaus went on his first overseas posting when he was appointed third secretary at the Australian Embassy in Nairobi, Kenya - reporting also on Ethiopia, Somalia, Uganda and Seychelles.

[citation needed] In 1991, he was appointed First Secretary, later Counsellor (covering legal, disarmament and Security Council) to Australia's Mission to the United Nations (UN) in New York (1991-1994).

[citation needed] From 1997–2000, Neuhaus was appointed as Australian High Commissioner to Nigeria – accredited also to Ghana, Sierra Leone, Senegal and The Gambia.

He had particular responsibility for the policy advice to Prime Minister John Howard as Chair of the Commonwealth Heads of Government Meeting (CHOGM) held in Coolum, Queensland, Australia in February 2002.

In October 2002, Neuhaus was appointed to the position of Director of the Political Affairs Division of the Commonwealth Secretariat in London, firstly under the Secretary General Sir Don McKinnon of New Zealand and then Kamalesh Sharma of India.

In 2015 he returned to the University of Cambridge as a visiting fellow at the Lauterpacht Centre for International Law where he worked on two projects - Reform of the Commonwealth Secretariat and Peace building in Africa.

[10] Neuhaus presented his credentials in the Netherlands on 29 August 2018 to his Majesty King Willem-Alexander,[5] and as Australia's Permanent Representative to the OPCW, to Director General Fernando Arias the same day.