Mold fouling during the crosslinking process of EPDM rubber compounds results in defects in compression-molded products and deterioration of process conditions. Moreover, subsequent cleaning of molds is expensive and causes a loss at production. The fouling of several types of steel and aluminum alloys, which represent molds with variously machined surfaces, was analyzed during 0–70 cycles of EPDM molding. Fourier transform infrared microscopy was used for investigation of fouling and paraffin oil (softener) and/or EPDM fragments were detected in vibrational spectra of fouling as the most probable components of it. Metal specimens with a grinded surface were found to be more resistant to EPDM residue deposition.