The Western-backed leader, beaming and wearing a black bomber jacket, walked up to the back cargo bay of a military transport plane that landed at a military airport outside Kiev in the dawn hours of today to hail the men.
He firmly shook hands and tightly embraced them - some young and others sporting greying beards - as they trundled down the steps wearing regular civilian clothes and knitted skull caps in the searing cold.
Ukraine's chronically underfunded army has been criticised heavily by the public for failing to stamp out a revolt that has claimed 4,700 lives and continues to threaten the former Soviet republic's very existence.
Poroshenko appeared to be addressing that rebuke by praising the men for "not breaking or changing and firmly keeping your military morale, demonstrating the best qualities of a Ukranian warrior".
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Kiev yesterday freed 222 insurgent fighters captured around the main rebel stronghold of Donetsk and its surrounding regions.
But the original deal - agreed with the help of European and Russian mediators in the Belarussian capital Minsk on Wednesday - called for the release of 150 state troops and 225 militants.
"Unfortunately, not everyone was released. Another four of your comrades will come back on (today)," Poroshenko said in reference to a much smaller prisoner swap expected to take place in another part of eastern Ukraine.
"The country will fight for each one of its faithful sons."
Today's swap was due to involve both sides' fighters captured in Donetsk's neighbouring breakaway region of Lugansk.