Revenues were up 1.9 times to VND52.4 trillion.
The company, which owns a 130,000-barrel-per-day refinery in central Vietnam, attributed the jump in earnings to the surging prices of gasoline.
For the first five months this year, gasoline prices in Vietnam had been adjusted upward for 13 times and were almost 50 percent costlier year-on-year, Deputy Prime Minister Le Minh Khai said.
The price of popular RON 95 gasoline peaked on June 21, at VND32,870 a liter, before falling to VND26,070 ($1.11) per liter on July 21.
First half revenues rose by nearly 80 percent to VND87.05 trillion.
The company is seeking permission for a $1.2-billion upgrade of Dung Quat, situated in the central province of Quang Ngai, to increase its capacity by 16.9 percent to 7.6 million tons a year.