"The situation has moved from red to orange, this is excellent news for us," Platini told reporters after an executive committee meeting at European football's governing body.
"Things are improving in Ukraine as well as in (co-hosts) Poland."
"I want to congratulate the Ukrainian authorities. All of a sudden they have found new hotels from nowhere, I'm not sure where they've sprouted up from but they have found them.
"It's wonderful for Ukraine to pass to orange but our ultimate goal is to get from orange to green."
UEFA has expressed doubts about Ukraine's ability to stage the tournament and has so far confirmed Kiev as the sole Ukrainian city able to host matches.
But the capital's staging of the final was made contingent on completion of delayed renovations at the Olympic Stadium.
Three other Ukrainian cities - Lviv, Donetsk and Kharkov - must be confirmed at a UEFA meeting on November 30 along with Kiev's right to stage the final.
UEFA has already granted four Polish cities the right to hold Euro 2012 matches.
Platini decried "huge infrastructure problems" in Ukraine in May, including airport infrastructure, transport networks and suitable accommodation for a huge influx of fans.
Ukraine and Poland were chosen as co-hosts in 2007.
Platini and other UEFA officials have said the tournament will not be withdrawn from either country but have suggested the distribution of cities hosting matches could be altered.
