A method of forming a solid matrix for use with surface-enhanced Raman spectroscopy is described. The method comprises the steps of: admixing a colloidal metal solution with a polymeric support medium to form a suspension; optionally depositing said suspension on a surface; and then drying the suspension to form the matrix. The polymeric support medium provides a plymer/sol suspension in which the sol particles are resistant to aggregation and precipitation. Upon drying the suspension shrinks to provide a mechanically-hard film subsequently usable to provide a sample for spectroscopic analysis.