[en]This paper investigates the relationship between energy prices and the real effective exchange rate of commodity-exporting countries. We consider two sets of countries: 10 energy-exporting and 23 non-fuel commodity-exporting countries over the period 1980-2011. Estimating a panel cointegrating relationship between the real exchange rate and its fundamentals, we provide evidence for the existence of « energy currencies ». Relying on the estimation of panel smooth transition regression (PSTR) models, we show that there exists a certain threshold beyond which the real effective exchange rate of both energy and commodity exporters reacts to oil prices, through the terms-of-trade. More specifically, when oil price variations are low, the real effective exchange rates are not determined by terms-of-trade but by other usual fundamentals. Nevertheless, when the oil market is highly volatile, currencies follow an « oil currency » regime, terms-of-trade becoming an important driver of the real exchange rate.[/en]