Minister for Foreign Affairs Simon Coveney is in Kyiv on Thursday for meetings with senior Ukrainian politicians and officials and to visit areas previously under Russian control.
Mr Coveney entered Ukraine from Poland on Wednesday night.
The Polish military provided assistance as far as the Ukrainian border, where he was met by Ukrainian special forces who are providing transport and security during his visit. He is also accompanied by a close protection team from the Garda Emergency Response Unit, and is travelling with the Irish Ambassador to Ukraine, Thérèse Healy.
Officials said Mr Coveney's discussions with the Ukrainian government would focus on how the State could continue to provide aid and assist Ukraine in its bid for EU membership. He will also discuss support for tougher EU sanctions against Russia.
Mr Coveney will report back on his visit to the UN Security Council, where the State currently holds a seat. His visit is the first by the foreign minister of any of the UN Security Council members since the Russian invasion of Ukraine began on February 24th.
The State has already provided more than €50 million in aid to Ukraine in humanitarian supplies and non-lethal military items such as rations and body armour. More than 20,000 Ukrainian refugees have made their way to Ireland so far.
The Republic was also an early supporter of Ukraine's bid for membership of the EU. Last week, Ukrainian president Volodymyr Zelenskiy paid tribute to the State's support for his country during an address by video link to both Houses of the Oireachtas.
It was expected that Mr Coveney would hold a press conference with the Ukrainian government later on Thursday.
Meanwhile, the US is to provide artillery systems, armoured personnel carriers and additional helicopters as part of a new $800 million military assistance package for Ukraine.
US president Joe Biden said he had given details of the new military assistance in a conversation with Mr Zelenskiy on Wednesday. "The Ukrainian military has used the weapons we are providing to devastating effect. As Russia prepares to intensify its attack in the Donbas region, the United States will continue to provide Ukraine with the capabilities to defend itself," Mr Biden said.
The presidents of Poland, Lithuania, Latvia and Estonia travelled by train to Kyiv to meet Mr Zelenskiy on Wednesday. Polish president Andrzej Duda told a news conference there: "This is not war, this is terrorism." He had earlier visited the town of Bucha just outside Kyiv, where the discovery of slain civilians following the withdrawal of Russian forces from the area has provoked a global outcry.