Partner, Dispute Resolution


Oleh Marchenko is a Partner chairing Disputes Practice of the firm. Oleh is recognized as a prominent practitioner in in treaty disputes and public international law. He advises and acts for Clients on contentious PIL issues and disputes, investor-state disputes and related negotiations, bilateral investment treaties, the Energy Charter Treaty, human rights, the laws of war, ICSID Convention, State attribution, immunities, State responsibility, international arbitration and cross-border litigation, ADR, WTO, Free Trade Agreements and International Trade Law.

Oleh concentrates on contentious matters which entail complex and novel PIL issues and high-stake public policy matters. His cases regularly make headlines in international and national media. Oleh acts for multinational Clients, such as Gilead, Philip Morris, MHP SE, U.S. Export-Import Bank, LafargeHolcim, Microsoft, in treaty and related disputes involving intricate issues at the crossroads of public international law and national laws.

Oleh regularly publishes on PIL issues. His recent articles were devoted to Execution Immunity and Collection Against Sovereign Assets: A Case for the Russian Federation (European Arbitration Review 2020), Occupation Nuances: Jurisdiction of Ukrainian Court in Legal Actions Against The Russian Federation Concerning Expropriation of Investments in the Occupied Territories [Crimea and Eastern Ukraine] (Yurydychna Gazeta 2020), Protection of Investments in International Armed Conflicts: A Case for Donbas (European Arbitration Review 2019), and Negotiations and Pre-Arbitration Settlements in Investor-State Disputes from a Ukrainian Perspective (The European Arbitration Review 2018). Oleh Marchenko is a regular speaker on PIL and treaty disputes.

In 2020, Oleh Marchenko won the Best Arbitration Practitioner in independent national research conducted by Liga Zakon Awards 2020. Best Lawyers International (in 2017-2021) ranked Oleh as the leading practitioner in Arbitration and Mediation in Ukraine. According to Legal 500 EMEA, Who’s Who Legal, and other world’s leading rankings, Clients and peers describe Oleh “the first-class professional” with “a superb reputation,” “a star individual,” “an exceptionally talented lawyer,” “a top-notch lawyer,” having an “impressive and profound expertise in public international law”, performing “superior work,” “open-minded and creative,” and having “a talent to explain and argue highly complex issues of public international law in a simple, clear and convincing manner.”

  • Career Experience:
    2013 – now
    Marchenko Partners, Partner
    2010 – 2013
    Ulysses, Managing Partner
    2001 – 2010
    Magisters, Partner
    1999 – 2001
    Deloitte, Senior Associate
    1997 – 1999
    Magisters, Associate
  • Degree in Business Law, Kyiv National Economic University
  • Degree in Economics, Sociology, Kyiv Mohyla Academy
  • Harvard University, Massachusetts (non-degree studies)
  • Thomas Aquinas College, California (non-degree studies)
  • International Bar Association
  • Ukrainian Bar Association
  • Ukrainian Arbitration Association

The Legal 500 EMEA 2021
recommends Oleh Marchenko
as a Leading Individual in Dispute Resolution

The Legal 500 EMEA 2021 recommends
Marchenko Partners in Dispute Resolution

Best Lawyers 2021 recommends Oleh Marchenko
in Arbitration and Mediation, and Litigation

The Legal 500 EMEA 2020 recommends
Marchenko Partners in Dispute Resolution

Best Lawyers 2020 recommends Oleh Marchenko
in Arbitration and Mediation

“Ukrainian Law Firms 2020.
A Handbook for Foreign Clients”
recommends Oleh Marchenko
as a notable practitioner
in International Arbitration

Liga Zakon Awards 2020
recognized Oleh Marchenko as the
Best Arbitration Practitioner, and
our Dispute Resolution team as the
Best Practice in Arbitration

The Legal 500 EMEA 2019 recommends
Oleh Marchenko in Dispute Resolution and Tax
for tax litigation and tax-related investor-state disputes

Best Lawyers 2019 recommends
Oleh Marchenko as one of the best in
Arbitration and Mediation, and Tax Law

“Ukrainian Law Firms 2019.
A Handbook for Foreign Clients”
recommends Oleh Marchenko
as a notable practitioner
in International Arbitration

Best Lawyers 2018 recommends Oleh Marchenko
in Arbitration and Mediation

27 Oct, 2020

On October 22, 2020, Marchenko Partners, jointly with the Business Ombudsman Council, organized a webinar devoted to an important issue for Ukraine: “When Court Decisions …

7 May, 2019

On March 22, 2019, the State Fiscal Service of Ukraine revoked UAH 635 Million tax claims against Philip Morris Ukraine Private JSC in accordance with …

9 Dec, 2019

Oleh Marchenko, Partner and Head of Dispute Resolution, and Anastasiia Kotliarchuk, Associate of the same practice, have prepared an article for Client Choice-2019 by Yurydychnna …

16 Mar, 2020

The Ukrainian National Rounds of the Philip C. Jessup International Law Moot Court Competition took place from 28 February till 1 March 2020. This is …

3 Dec, 2018

The illegal annexation of Crimea by the Russian Federation in April 2014, followed by the armed conflict in Donbas that has been financed, supported and …

8 Aug, 2019

Verkhovna Rada may restrict patent protection for derivative medicines in violation of the international obligations of Ukraine. Read more in the article of Oleh Marchenko and …

28 Aug, 2019

The 4th Jessup Summer School marked our 10th anniversary in Jessup as National Organizer. During this time, we were able to shape an event, which …