The late-Hercynian batholith of the Catalonian Coastal Ranges (NE Spain) represents a typical high-K calc-alkaline association. In the Tossa de Mar area, the calc-alkaline rocks are intruded by a highly acidic leucogranitic complex, which consits of various plutonic and subvolcanic intrusions cut by related felsitic, granophyric, and porphyric dykes. The rocks of this complex show many petrological and geochemical characteristics of alkaline granites. The data suggest that these leucogranites may not be related to the calc-alkaline association by a simple differentiation process. Their extreme acidic composition, their shallow emplacement, and the lack of related intermediate and basic rocks, suggest a crystallization from an ascending water under-saturated acidic magma generated at deep levels.