As police advanced the call went out and thousands more citizens rushed to the square.
Both times the protesters were successful in pushing back the police who tried to remove them from Independence Square.
Dozens, on both sides, were injured, including opposition lawmakers and one Orthodox priest.
It is unclear how the government will respond to the police's failure.
On Monday, the police cleared out many smaller protests in Kiev and other cities.
Protests have been going for most of a month and Sunday saw the biggest yet, with over one hundred thousand in the capital city.
The people are demanding that President Viktor Yanukovych resign.
He angered the public when backed out of signing a trade agreement with the European Union, and instead announced that he would seek closer ties with Russia.
Many Ukrainians worry that Yanukovych is taking their country back under Russian influence and fear a loss of their independence from their former Soviet masters.
The protests have gained steam since three former presidents backed them, last week.
