[2] In 1989, he defended his thesis on Marxist social philosophy, supervised by Marek Siemek.

In 2001, he gained post-doctoral degree (habilitation), presenting a book on dissolution of the Soviet Union.

[5] Marciniak has been a member of the Polish-Russian Group for Difficult Matters,[6] and the presidential National Development Council (since 2010).

[7] On 13 October 2016, he became Poland ambassador to Russia,[8] presenting on 9 November 2016 his letter of credence.

[10] His brother,[11] Piotr Marciniak, was a member of Parliament of Poland (1993–1997), ambassador to Moldova (2000–2005), as well as consul-general in Irkutsk (2008–2009) and Saint Petersburg (2011–2015).