On 24 January 2022, he was elected the President of the Parliamentary Assembly of the Council of Europe (PACE), initially for a one-year term.

[3] In 1973 Kox finished an economical-judicial study programme at the School for Higher Economics & Administrative Sciences in Eindhoven.

[8] In 2018, Kox put through a proposal that focused on categorically beating back child poverty in the Netherlands.

[12][13] In addition to his work in parliament, Kox was a member of the Dutch delegation to the Parliamentary Assembly of the Council of Europe from 2003 until 2024.

[14][15][16] Kox also led multiple missions as an international election-supervisor in Bosnia (2010, 2014), Russia (2011, 2012), Turkey (2015) and Georgia (2020).

[18] On 28 September 2021 Kox was nominated by the UEL-group as President of the Parliamentary Assembly of the Council of Europe for 2022 and 2023, on the basis of the 2008 rotation-agreement between the five political groups in PACE.

As President he convened an urgent joint committee meeting with the CM and an extraordinary session of the Assembly, on the basis of which Russia was first suspended, then expelled from the Council of Europe.

[20] According to Kox Russia, by invading Ukraine,  had crossed the 'red line' of Europe's oldest and broadest treaty organisation, created in the aftermath of World War II to preserve and protect peace by means of peaceful cooperation on the basis of respect for the rule of law, human rights and democracy.

Assembly-President Kox called at the opening ‘restoring, strengthening and perhaps re-inventing European democratic security and rules- based multilateralism against aggressive unilateralism has become an existential challenge and a main reason to meet here today.’[24] The Heads of State and Government of the 46 member States decided in Reykjavik on a future roadmap [25] for the Council of Europe, which will celebrate its 75th anniversary in 2024.