"Shame" the crowd chanted, late on Wednesday in the city's central Independence Square after Prime Minister Viktor Yanukovich was declared the official winner of the weekend vote.
The crowd have vowed to stay until opposition leader Viktor Yushchenko is named president.
"We are many, we are not going to be beaten!"
The central election commission gave Yanukovich a three-percent victory over Yushchenko in the election that has been condemned by both the European Union and the United States for alleged fraud.
The crowd roared when Yushchenko appeared before them, and refusing to concede defeat, called for a defiant show of strength by the opposition.
'People's final hope'
"Yushchenko is our last hope, we are his last hope. He is our leader and we are his instrument," said Sergei, an 27-year-old engineer from Kiev.
"We are going to stay here to the end. It may be cold but there are hundreds of thousands of us here standing up for the future of our country."
Yuri, 29-year-old engineer
Neither the declaration of the pro-Russian Yanukovich as the winner of the election nor the sub-freezing temperatures appeared to have dampened their spirits or resolve.
"We are going to stay here to the end," said Yuri, a 29-year-old electrician. "It may be cold but there are hundreds of thousands of us here standing up for the future of our country."
"We don't accept the results, they were clearly falsified," said Dmitry, a 25-year-old car mechanic.
"A government must listen to the people, but this one showed that it won't listen to us. We are going to stay here until we get one," he added.
Wearing their trademark orange colour, opposition supporters danced and sang to keep warm and their spirits high as snow fell gently on the square.
Yushchenko called on supporters
to continue their protests
Despite their anger at having the election "stolen" from them, non-violence was universally espoused.
"We are against violence. This must be done peacefully and democratically," said Sergei.
"We need a government that respects us, respects our choice," said Larissa, who has been attending the demonstration off and on for the past three days with her fellow employees from an electrical goods shop.
"We are here because we worry about the future of our country, the future for our children," said her co-worker Tatyana. "We hope this will be resolved peacefully."
Larissa expressed confidence that in case of a confrontation the police, who have massed around the edge of the city, would not use violent force against opposition demonstrators.
"I don't think the police would shoot us. They are Ukrainians just like us."