The French president met Italian Prime Minister Matteo Renzi in Paris early today and will later head to Moscow.
Hollande has been on a whirlwind tour seeking to build a coalition to crush IS in Iraq and Syria but has won few concrete pledges so far, and his campaign has been further complicated by a spat between Russia and Turkey over a downed jet.
Renzi offered only vague support for "a coalition of greater and greater strength that is up to the task of... The destruction of Daesh", using another name for IS.
German Chancellor Angela Merkel yesterday pledged to stand beside France after talks with Hollande, saying she would act "swiftly" to see how her country can help in the fight against terrorism.
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The French and German leaders each laid a pink rose among the tributes of flowers and candles in Place de la Republique, the Paris square that has become a rallying point since the bloodshed.
Meanwhile in Britain, Prime Minister David Cameron will set out the case for his country to extend its air strikes against IS from Iraq into Syria ahead of a vote by MPs next week.
The British premier has called IS a "direct threat to our security at home and abroad".
He met Hollande on Monday and offered France the use of a British air base in Cyprus for flying missions against the jihadists.
While Cameron said he "firmly supported" the French leader, Hollande got a cooler response from US President Barack Obama, who is reluctant to intensify military action without a clear strategy or political track in place.
Turkey's military said the following day it did not know the jet was Russian and that it was ready for "all kinds of cooperation" with Russia, after Moscow called the incident a "planned provocation".