Vladimir Putin ordered it to start tomorrow - to mark the Russian Orthodox Christmas holiday this weekend.
Moscow says the measure will allow troops to go to religious services.
It's the first truce in nearly 11 months of conflict.
But Svitlana Zhereva, who lives in Kyiv, is sceptical about Russia's intentions:
"Shall we believe the Russians? On the one hand, they have given their blessing to the war, and to kill. And on the other hand, they want to present themselves as saints who are against blood spilling. They should be judged by their actions."
