Surface-Enhanced Infrared Absorption spectroscopy (SEIRA) methane sensors enable the detection of low gas concentrations under ambient conditions, making them suitable for applications in medical diagnostics, industrial process control, and safety monitoring in the food and energy industries. This research work focuses on the development and characterization of a SEIRA-based methane sensor. The physical phenomena of SEIRA can be used to enhance the Infra-Red (IR) absorption band of methane at 3016 cm^−1, achieved through the excitation of surface plasmon polaritons in a gold microstructured surface combined with a microporous storage layer that locally increases methane concentration near the metal. It is researched how to obtain a homogeneous microporous layer on the gold surface by realizing a Self Assembled Monolayer (SAM) with molecules presenting thiol groups, such as thiophenol or 7-mercapto-4-methylcoumarin.