The dynamic mechanical behavior of materials based on 1,2-dihydro-1,2-methanofullerene[60]-61-carboxylic acid (F-CA), poly(styrene-co-4-vinylpyridine) and poly(styrene-co-butadiene) was studied. The interaction between the carboxylic acid group of F-CA and the pyridine group as evidenced by X-ray photoelectron spectroscopy (XPS) ensures a good adhesion between F-CA and the polymer matrix. The storage modulus of the polymer matrix is significantly increased by the incorporation of F-CA, and F-CA is a more effective reinforcing filler than unfunctionalized C-60.