A simple procedure for preparing gold-coated silica capillaries for use in electrospray ionization mass spectrometry is described. The tip of the capillary is mechanically tapered to a fine point, and a thin film of gold is vapor deposited on the outer surface following treatment with an organofunctional silane. The performance characteristics of these durable capillaries as continuous infusion sources are examined, and their utility in on-line capillary electrophoresis mass spectrometry is demonstrated.