The article analyses the evolution of the names of the Catalan municipalities, as a part of the process of contemporary political centralization of Spain. To check the degree of Spanish interference, Catalan writing before the Nueva Planta (new system of government of Catalonia, in 1715) is compared with the official written form in the middle of the 19th century. The same methodology is applied to the French Catalonia. Altogether we analyzed 1,304 place names. It can be concluded that in Catalonia (Spain) there was a major continuity of the spelling (76%), compared to just a 33% in the territories joined to France. There are 4 degrees of alteration of place-names; the maximum distortion reaches only 3.3% of the cases by the Spanish side, compared to 51.2% in France. The abundant French cartography referred to Catalonia shows the same proliferation of deformed toponyms. Dades primàries associades a l'article http://hdl.handle.net/10459.1/62595