A defence source says the Harper government is expected to announce the deployment of training troops — possibly over 100.
Most of them are expected to be housed at an existing NATO training centre located in Yavoriv, in the western portion of the embattled European country, near the Polish border.
The troops will join American and British soldiers, likely in mid-May.
Prime Minister Stephen Harper and Defence Minister Jason Kenney are expected to announce the long-anticipated move Tuesday at National Defence headquarters.
It is anticipated the Canadians will offer Ukrainian troops their expertise in countering mines and improvised explosives devices, skills painfully learned during the five-year combat mission in Kandahar.
The new mission could also involve instruction on logistics and military policing, something former defence minister Rob Nicholson hinted at last winter when military planners visited the country to determine how best to help.
How long the training mission will last is unclear.
The Canadians will be far from where Ukrainian troops are battling pro-Russian separatists in the east.
Kenney dropped a broad hint in February that the government was open to joining the international initiative.
The U.S. military has deployed 800 troops to train three — possibly four — battalions in western Ukraine and the British recently sent 75 soldiers to give instruction in command procedures, tactical intelligence and battlefield first aid.
Both Washington and Ottawa have been under pressure to ship lethal military aid to President Petro Poroshenko's government, which has been struggling to hold a shaky ceasefire together with rebels.
The Pentagon delayed the training program for Ukrainian soldiers last month to avoid giving the Kremlin an excuse to scrap the peace deal struck in February.
There have been widespread reports in the last week that Russian-backed separatists are preparing for a spring offensive in the southern region, a sign the conflict could re-ignite.
Russia could very well consider the deployment of NATO trainers as a provocation at a time when it has rattled most of Europe with massive, snap military exercises along its borders involving tens of thousands of troops.
It strikes at the heart of the dilemma faced by Western leaders: how to stop Russian President Vladimir Putin's slow-motion dismemberment of Ukraine without provoking a major war.
The announcement of Canada's participation comes just days after Estonian President Toomas Hendrik Ilves told a British newspaper that he was in favour of NATO deterring Russia with the permanent stationing of combat units in the Baltic states.
Four Canadian CF-18s took part in NATO air policing missions to protect the Baltic States last year, and a company of soldiers belonging to the Royal Canadian Regiment are currently involved in exercises in the region.