Half-year profits fell to 305.8 billion rubles (10.6 billion dollars), compared to 609.4 billion rubles (21 billion dollars) in the first six months of 2008, the company said in a statement.
It said net income dropped 6.6 percent on a year earlier to 1.6 trillion rubles (56.6 billion dollars).
Sales of gas to Europe and other states had increased 6 percent as higher prices across the world compensated for drastic falls in export volumes, it said.
At the same time, operating expenses and financial charges rose sharply as the cost of purchased gas soared 105 percent, reflecting an increase in prices for gas from Central Asia.