An electrospray system and procedure has been developed for the routine preparation of thin films of involatile molecules for analytical measurements. An anode-cathode design has been developed and conditions for reproducible performance have been established. Solvent systems for polar and nonpolar molecules have been investigated and electron microscopy measurements have been made on the microstructure of the deposits and fraction of surface coverage. The method does not appear to degrade thermally-lablle molecules.The preparation of thin solid films of involatile molecules is a problem frequently encountered in analytical measurements that are sensitive to the nature of the sample surface. The problem is particularly important in "solid state" mass spectroscopy where ions are produced at the surface of a solid film and intensities depend on the fraction of the surface covered. This includes field desorption (1), 252Cf-plasma desorption mass spectrometry (PDMS) (2), secondary ion mass spectrometry (3), and laser desorption (4).Various techniques have been employed in the past for producing thin films on a solid backing. These include high