On 28 October 2021, the International Centre for Settlement of Investment Disputes (ICSID) registered a new request for arbitration proceedings brought against Ukraine by SREW NV (SREW). SREW, which owns the 110-megawatt Dnepro-Bugsky wind power station in southern Ukraine, is claiming that Ukraine’s reforms to its tariff regime are in breach of the BLEU (Belgium-Luxembourg Economic Union) - Ukraine bilateral investment treaty (BIT). This follows the claim earlier in the year by Modus Energy International (Modus Energy), a Lithuanian investor in three solar power plants in Ukraine, which filed SCC arbitration proceedings against Ukraine under the Energy Charter Treaty (ECT). Modus Energy is claiming, by way of its Dutch subsidiary, that Ukraine has breached the ECT through the adoption of Law No. 810-IX, a legislative reform which reduced guaranteed feed-in tariffs (FITs). It is reported that Modus Energy is claiming damages of approximately EUR 11.5 million. Yet, the claims by SREW and Modus Energy may only be the first set of claims in a potential wave of investment treaty claims, under the ECT or other bilateral investment treaties, that Ukraine may face over recent amendments to its FIT regime. Elementum Energy, a UK investor, has already filed a notice of dispute under both the ECT and the UK-Ukraine BIT and it is reported that investors from Norway, South Korea and Turkey are also considering or have already filed similar trigger letters in response to Ukraine’s legislative reforms. In this Client Alert, we discuss the recent legislative reforms to Ukraine’s FIT regime which have already given rise to the disputes referred to above. We also consider the claims which Ukraine could face in the context of similar claims which other States have faced in response to the reduction in FITs.