In this report we describe the theories for the increased infrared absorption ability of molecules applied to a substrate coated with a thin metal film. This effect is called surface-enhanced infrared absorption (SEIRA). With transmission spectroscopy we experimentally examine the possibilities for documententation of SEIRA for p-NBA applied to a calciumflouride window coated with goldfilms with thicknesses of 4.5 nm, 8 nm and 16 nm. Furthermore we examine the reproducibility of each series. We find that there is an enhancement in the absorption of p-NBA which can be ascribed to a SEIRA effect and that this enhancement is increased with increased gold film thickness. It is concluded that the reproducibility is sufficient for documentation of the enhancement.