Adsorption isotherms of PMMA onto conducting hydrogensulfate-doped polypyrrole (PPyHSO4) from chloroform and CCl4 have been determined by means of time-of-flight secondary ion mass spectroscopy (ToF-SIMS). PMMA adsorption is of the Langmuir-type in both solvents. CCl4 yields a much stronger adsorption of PMMA, a result that is discussed in terms of acid–base properties of PMMA, PPy and the solvent as well as the solvent power.