A novel procedure for fabricating silica emitters for electrospray ionization-mass spectrometry (ESI-MS) has been developed. Conventionally, to create a silica emitter, a fused silica capillary is heated and pulled until the capillary breaks, causing the I.D. and O.D. of the capillary to taper down to a small aperture several micrometers in diameter. While these small emitters can be used to produce stable electrospray at low flow rates (<200 nL/min), where sensitivity is enhanced, there are several challenges associated with their use. First, the mechanical process of tip pulling is difficult to control, particularly when performed by hand, leading to poor reproducibility. Also, because the I.D. of the capillary decreases along its length, particulate matter can easily become trapped, blocking flow and ruining the emitter. Finally, it has been shown that the Taylor cone is supported by the O.D., rather than the I.D., of ESI tips, and the thickness of the capillary wall of pulled tips requires an even smaller I.D. at the aperture than would otherwise be required for stable operation an low flow rates. The procedure disclosed here uses chemical etching to create tips with a tapered O.D. but a fixed I.D., which prevents clogging and reduces dead volume. The chemical, rather than mechanical, process improves reproducibility, and the walls at the end are extremely thin, providing for stable electrospray at flow rates of 5 nL/min for a 5 ƒÝm I.D. tip.