Introduction of various organic functional groups onto organic thin films is a first step in their applications to sensors, catalysis, and nanotechnology in general. In this paper, we studied the reactivity of vinyl-terminated self-assembled monolayers (SAMs) of undec-10-ene-1-thiol on gold toward olefin cross-metathesis (CM). Vinyl groups on SAMs were successfully converted into alpha,beta-unsaturated carbonyl groups by CM with acrylic acid, methyl acrylate, and acrylamide, and CM was confirmed by Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and contact-angle measurement. Ruthenium-catalyzed olefin CM has offered a versatile strategy for functionalization in solution chemistry with mild reaction conditions and a high compatibility in functional groups. Our result shows that various useful functional groups can be introduced to SAMs on gold (and other solid surfaces) by olefin CM and suggests an alternative to the synthesis of desired molecules in solution.