The franczone (although perhaps it should now be called the francophone “eurozone”) includes France, Benin, the Central African Republic, Burkina Faso, Cameroon, Chad, Congo, Gabon, Equatorial Guinea, Ivory Coast, Guinea-Bissau, Mali, Niger, Senegal and Togo, and the Comoros Islands. The zone (known as the “Communauté Financière Africaine” or “CFA”) is a vestige of colonialism that was created in 1948, and it enables the French Republic to exert a strong influence over its former colonies. In particular, France guarantees the CFA currency’s convertibility to euros (1 French franc used to be the equivalent of 50 CFA francs) and, in exchange, the former French colonies agree to deposit 65% of their foreign exchange reserves with the French Treasury. Should this account with the French Treasury be overdrawn, France reserves the right to veto the CFA zone’s monetary policy.
The rationale behind the CFA—in addition to solidifying France’s economic power over a portion of Africa—was to provide increased fluidity in trade as well as monetary stability and integration in Africa. For example, if 65% of a country’s foreign exchange reserves must be accounted for in a treasury, a constraint is placed on government spending (thereby making rampant borrowing and over-spending more difficult for African heads of state). Devaluation of the CFA currency is also less likely.
The CFA (which is actually divided into two regions: the West African Economic and Monetary Union and the Central African Economic and Monetary Community) is nonetheless a frequent target of criticism. Because the CFA currency is pegged to the stronger EU euro, CFA member countries lose some macroeconomic control: they cannot use exchange rates to influence investment or export competitiveness. Moreover, the tie between the French currency and the CFA currency (and the stagnant nature of this exchange rate) means that the prices of CFA member countries’ exports are higher than they might otherwise be. This harms local African businesses and leads to protectionist African trade measures, including tariffs and subsidies, in order to enable local businesses to survive. In addition, the notion that the CFA has led to greater African integration should not be overstated. The Cameroonian economist, Celestin Monga, has pointed out that “a visa is required for movement [between] member countries, and often such visas can be obtained only from the French Embassy.”
In the words of one Senegalese economist: “the end result of the partnership between France and its former African colonies has been spectacularly lopsided. France has secured a vast market for its products, a steady supply of cheap raw materials, repatriation of the lion's share of local savings, unrivaled political influence, a strategic presence with military bases occupied free of charge and the certainty that it can rely on its African allies' diplomatic support. But for the Africans, the partnership has meant weak trade performance, tight money, high interest rates, massive capital flight and mountains of debt whose repayment prevents higher investment in education, training, health, food production, housing, and industry.”
For further information on the CFA and France (in English), look at this, this and this site.