This article focuses on the rheological, mechanical and optical properties of polydimethylsiloxane (PDMS) relevant for microelectromechanical systems (MEMS). In view of the limited amount of published data, we analyzed the two products most commonly used in MEMS, namely RTV 615 from Bayer Silicones and Sylgard 184 from Dow Corning. As far as rheological parameters are concerned, the viscosity and spin curves were measured. With regard to mechanical properties, we focused on the measurement of the inconstant elastic modulus up to 115% strain. For the optical characterization we concentrate on the optical dispersion and the wavelength-dependent damping coefficient.