The analysis of external economic relations of Russia reveals a paradox: while Europe is the main trade and direct investment partner of Russia, this is far from being the case concerning its currency’s role in Russia's financial activities. The dollar is much preferred by economic agents for financial operations. This paper proposes a disaggregated approach to this issue by separating the ‘means of exchange’ and ‘store of value’ components of the use of substitution currencies. The influence of three main factors (inertial component, real trade relations and exchange rate fluctuations) on the relative demand for the euro by Russian economic agents is tested for the period 1999-2004. Finally we suggest a theoretical interpretation of the results based on the conventions theory approach.