The Belarussian ruble strengthened on Thursday to 14,960 to the dollar from 15,010, its first gain on the national currency exchange in 2015 after suffering from fallout from economic turmoil in its main trading partner, Russia.
The Central Bank has devalued the ruble 18 percent since the beginning of last week, part of a series of emergency steps to defend itself from a sharp weakening of the Russian ruble.
The Belarussian currency has lost almost 28 percent in value since mid-December, around the time when Western sanctions over Ukraine and a sliding oil price pushed Russia's ruble to record lows.
The Central Bank in Minsk will base its official exchange rate for Friday on the rate set on the currency and stock exchange on Thursday.
It has said it will only step in to protect foreign exchange rates using its gold reserves at times of peak volatility.