Romania floated 9.84 percent of Petrom oil group on the Bucharest stock exchange Monday, a public offering expected to earn it 610 million euros (870 million dollars).
A total of 5.5 billion shares are up for grabs, with 15 percent of them set aside for retailers.
Austria's OMV holds 51 percent of Petrom, a stake that cost it barely 1.5 billion euros back in 2004. Petrom is now valued 5.3 billion euros.
The Romanian state owns a 21 percent stake and Fondul Proprietatea, an investment fund set up to compensate Romanians whose assets were seized under communism, another 20 percent.
Petrom, the biggest oil and gas group in Eastern Europe, holds major gas and oil reserves and owns 540 gas stations in Romania and 270 in neighbouring Moldova, Bulgaria and Serbia.
The offering is the first in a series that cash-strapped Romania plans to launch this year.
The state will float 10-percent share packages in nuclear energy company Nuclearelectrica and hydro-electric power company Hidroelectrica, and 15-percent packages in electricity transporter Transelectrica, gas transporter Transgaz and gas producer Romgaz.
The five IPOs should bring Romania up to 4.0 billion euros (5.7 billion dollars), analysts say.
Prime Minister Emil Boc said Saturday the listings are aimed at consolidating Romania's economic recovery, after two years of severe recession.