As a first step after entry into force of the provisional application of the EU-Ukraine Association Agreement, Ukraine signed on 20 March 2015 an agreement to join Horizon 2020 on equal terms with EU Member States and other associated countries.
The agreement will come into force once it is
ratified by the Ukrainian Parliament, but Ukrainian legal entities can already
participate in all Horizon 2020 actions funded under the 2015 budget, as this
association covers the years 2015-2020.
Interestingly, under the Seventh Framework Programme, Ukraine was one of the top ten most performing third countries, including on areas such as nanosciences, nanotechnologies, or biotechnologies; and space.
More information available here.