The Taoiseach is expected to hold his first face to face meeting with Ukranian President Volodymyr Zelenskyy in the capital Kyiv today.
Micheál Martin travelled by train overnight and will take part in a series of engagements, including a visit to the Ukranian parliament.
President Zelenskyy invited Mr Martin to Ukraine, after they spoke on the phone two weeks ago.
Fianna Fail MEP Barry Andrews says it's the first time an Irish Taoiseach has visited the country.
"The timing of course is really extraordinary," he continued.
"We are going through one of the most barbaric attacks on international law.
"The people of Ukraine are experiencing incredible loss and hardship right now.
"And, I think the Taoiseach really does represent all the people of Ireland in being present and having engagement with President Zelenskyy."
