Russian gas exporter Gazprom said it had received a $15 million prepayment from Ukrainian state energy firm Naftogaz, averting a possible cut in supply, at least for a few days.
The money is enough to cover 45.6 million cubic metres of gas, or about five days of supply at current rates of delivery, Gazprom said by e-mail.
Gazprom had warned that supply to Kiev could be cut off as soon as Friday if no payment was made.
Any possible cuts in gas supplies to Ukraine could have a knock-on effect for the European Union, where Russia meets one third of the fuel demand. Around 40 percent of Russian gas to the EU goes via Ukraine.
The two former Soviet republics have been engaged in a spat over Russian gas pricing, debts and other key terms. Both have lodged their appeals with the Stockholm arbitration tribunal, which is not expected to issue a ruling before 2016.
Russia puts Ukraine's debt for gas supplies at $2.4 billion.
The gas spat has been at the heart of the wider dispute between Russia and Ukraine.
In early 2014, pro-Moscow president Viktor Yanukovich fled from Kiev following fierce street protests after he reneged on a promise to forge tighter ties with Europe, choosing closer cooperation with Russia instead and securing much cheaper gas supplies.
After his abrupt departure, Russia annexed Ukraine's Crimea peninsula in March, while a pro-Moscow insurgency erupted in eastern Ukraine, where some 6,000 people have since been killed.
Russian President Vladimir Putin said on Wednesday he did not want a repeat of pay disputes that have seen Russia cut off supply to Ukraine three times in the last decade, leaving many European states without gas in the middle of winter.
Once Gazprom's largest export market, Ukraine has reduced its reliance on direct gas imports from Russia in recent years.
Its imports from Russia in January and February fell by half from a year earlier, according to gas transit monopoly Ukrtransgaz.
Russia and Ukraine have agreed to discuss a new gas deal before a current temporary pact expires at the end of March.
