At the ceremony, Ukrainian Deputy Prime Minister Oleksandr Vilkul paid homage to the "hundreds of thousands" of people who sacrificed their health or their lives to cope with the crisis.
Other top Ukrainian officials, including President Viktor Yanukovych and Prime Minister Mykola Azarov, are participating in events to mark the 27th anniversary of the accident, which released radiation equivalent to 500 Hiroshima atomic bombs.
Yanukovych said the total cost of the incident for his country over the last 27 years has been almost $180 billion.
Anniversary Also Marked In Central Asia
Elsewhere, several Central Asian cities have been marking the 27th anniversary of the 1986 Chornobyl nuclear-plant disaster.
In a ceremony in Kyrgyzstan's capital on April 26, Bishkek, Mayor Isa Omurkulov and diplomats from the Russian, Belarusian, and Ukrainian Embassies laid flowers at a monument commemorating the disaster's victims.
A similar ceremony was held in Kyrgyzstan's southern city of Jalal-Abad.
In several cities in neighboring Kazakhstan, local citizens and Chornobyl veterans also honored the victims.
Dozens of Chornobyl veterans and their supporters rallied in Kazakhstan's western city of Oral demanding benefits and financial support from the government.
More than 50,000 of some 600,000 so-called Chornobyl liquidators, who participated in the effort to contain the disaster, were from five Central Asian republics.
Source: Radio Free Europe