SU8-carbon nanotube composites have been produced to enhance the mechanical, electrical, and thermal properties of SU8 photoresists. Homogeneous composites materials have been obtained when multiwalled carbon nanotubes (MWCNTs) functionalized with COOH groups were used. Indeed, COOH groups can react with the epoxy ring of the SU8 molecule yielding an improved interaction between carbon nanotubes (CNTs) and the polymer matrix. Impedance spectroscopy was used to study the conducting percolation path in the composites, that is the quality of the nanotube dispersion in the epoxy matrix. It turns out that propylene glycol methyl ether acetate (PGMEA) as well as gamma-butyrolacton (GBL) are very suitable solvent to prepare SU8-MWCNTs composites of good homogeneity. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim